r AD A-Ü06 735 DISTRIBUTED COMPUTATION AND TEN EXRELATED ACTIVITIES ßo1r Be ranck a rd New ma n Incorporated Prepared for Advanced Research Projects Agency Februarv 1975 DISTRIBUTED BY KTm National Technical Information Service U S DEPARTMENT OF COMMERCE lest - Available 1 Copy 084137 BOLT BfcRANEr D CONSULTING vÄ E AND ' E I O P M NEWMAN f N T 5 BBN Report No 3012 c S E i A R H C c H February 197 CO • DISTRIBUTED COMPUTATION AND TENEX-RELATED ACTIVITIES J Quarterly Progress Report No 1 1 November 1974 to 31 January 1975 DOC B _ The views and conclusions contained in this document are those of the iuthors and should not be interpreted as necessarily representing the official policies either expressed or implied of the Advanced Research Projects Agency or tae U S Government Thxs research was supported by the Advanced Research Projects Agency under ARPA Order No 2901 Distribution of this document is unlimited It may be released to the Clearinghouse Department of Commerce for sale to the general public c NATIOIMAL TECHNICAL INFORMATION SERVICE CAMBtfDGE WASHINGTON DC CHICAGO HOUSTON lOS ANGtlES SAN FtANCISCO 7 BBN Report No 3012 Bolt Beranek and Newman Inc TABLE OF CONTENTS Page 1 I INTRODUCTION II DISTRIBUTED COMPUTATION A TI Access Control and Accounting System B RSEXEC Program Execution Environment C Management of Distributed Data Bases III TENEX RELATED ACTIVITIES A Protocol Development B Security ' C Distribution of TENEX Version 1 33 D BCPL 8 8 16 20 25 IV COTCO ACTIVITIES A Background B Project Activities C MAILSYS D Jocumentation E MAILER and FTPSRV TENp Capabilities 27 27 31 33 3f 35 33 ' mas mm TO CHANGE 3 3 5 6 BBN Report 3 U2 I Bolt Beranek a-id Newn an Inc Introduction Durinq this oua ter most of our work in was directed toward bringing distributed progressed file more implementation svstem and slowlv than worK on the planned However and documented a method non-trivial type of distributed mulciple coyy is to a oretotyoe of a program execution eiviroument that includes the completed method orogram-level the coupled message service projects RSEXEC distributed file system has been completed have conioutinq the TIP login and accounting svstem hs a result into ooerational status distcihuted be In addition for data we maintaining base a This used both for maintaining multiple copies of the Network US L Data Base as reouired by the TIP login system and for maintainina redundant message files for users of the coupled message service During this aua er we also compleced a lEMEX imolementatior of the Internetwork liansmission Control Program specified by Kahn and CerC in the May 1974 oroqram IEEE Transactions on Communications This will suppo- _ planned Internet expriments between BBN-TENSX i PDP-11 at Stanford University and a PDP-9 at Uni ersiuy College London The January distribution of TENEX Svstem 1 33 includes a resource allocation facility called the oie-slice scheduler which permits the facilities administration to slice a TENEX luaranteed novel portions of system into CPU service for each irouo of suoscribers Tais f cilitv will make it possible to olan reasonable allocation of -1- 3BN Report 3012 scarce TENEX Bolt Beranek arid Newman Inc resources thcouqhout research projects -2- the RPANL'T to various ARPA B 5 ■ Report 3012 II Bolt Beranek and Newman Inc Distributed Computation A TIP Access Contiol and countinq System At the request Compute' Systems of the Division ARPA at office BBN we and together with the have developed a login and accounting system for ARPANET TIPs see 53N reports 2869 and 2976 Prior to development of this system anyone with a terminal and data set who knew the telephone number for a TIP dial-up and uncontrolled access to the ARPANET port had free TIP login corrects this situation by requiring a TIP user to establish his authorisation to use the network by supplying a valid network user name and oassword TIP login and accounting was implemented existing TIPs TIPSER-RSEXEC system as well as other thought of as host to support functions by what are 2607 distribute In the TIPSSR-RSfiXEC system order load is meet among reliability participating implemented as a multiple TIPSER-RSEXECs ACTSERs and monthl j network requirements TENEX distributed multiple software data for login collection reducing summaries -3- usually reoorts 2544 and to hosts the multi-comouter The login system consists of three distinct components regular to the providing a means for sharing the resources of ARPANET TENEX hosts see 3BN and uoon TIP3ER-RSEXEC makes it possible for mini-hosts ''large y building but server server related Processes processes accounting data to produce RAN Reoort 3012 Bolt Beranek and Newman Inc Whenever a user activates a TIP port initial the TIP uses a connec iion mechanism see BBN reoort 2507 to select one of the TIPSER-RSEXEC Processes to authenticate the user successfully broadcast If the user suoolies a valid network-user name and oassword to the TIPSER-RSEXEC he is granted continued access tc network and the standard TIPSER-RSEXEC functions the TIP the In addition the TIPSER-RSEXEC transmits the user's uniaue Network ID code to the TIP fen- accountinq ourooses and makes a user login entry into an ' incremental TIP accountinq data file In order to use a network service host after loqqinq into the TIP a user must disconnect from the TIPSER-RSEXEC instruct the TIP to connect to the target host and then login to the tarqet host After the TIP receives the TIPSER-RSEXEC it activates user's remain active the user's it transmits code from the session These until the user terminates the TIP session Periodicallv the TIP executes an accounting whereby ID 'connect time and outqoinq message counters to accumulate usage data for counters uniaue usaqe data checkpoint accumulated since Procedure the last checkpoint for its active users to an ACTSER orocess selected much like the TIP selected a TIPSER-RSEXEC The ACTSER process stores the checkpoint daua in an incremental TIP accountinq file for later processing The collection of incremental accountinq the bDse ACTSER orocesses The reduction of is a data files maintained by larqe distributed and seqmented data in that -4- distributed data base to F33N Reoort 30i2 produce which Bolt Beranek and Newman Inc oeriodic executes accounting within the summaries is accomplished by software environment provided by the RSEXEC distributed file syst At present TIP access cont oJ and accountinq the expense of first TIP to use a loqin to the TIP and then to the target host planned step in the evolution of eliminate acnieved the at placinq an additional access control check between TIP users and the network service sites they plan must is second loqin the bv TIP3ER-RSEXEC user The next system is to extending the effect of the first login to include target host login 3 RSEXEC Program Execution Eiivironment The prototype version of the RSEXEC orogram execution environment makes the features of the RSEXEC distributed file system « e BBN reoorts 2404 oroirams run within this environment application programs When 2607 and 2670 available to executing such as text e itors and comoilers can uniformly access files both local nnd remote without regard to the actual network location of the files The TENEX JSYS trap mechanism set BBN report 2721 RSEXEC to programs calls made provide the distributed RSEXEC arranges to intercept certain operating system bv application orograms running under its control intercepted before the local -5- by file environment to executing examole certain file operations initiated by are is used TENEX api iication monitor acts For orograms on them QBN Report 3012 Bolt Beranek and Newman Inc Ooeratiois that can be handled locally ire passed local TEMEX ncnitor by RSEXEC Whenever directly a file to the operation is initiated that reauires access to a remote file RSEXEC transmits a reauest across the network to a cooperatinq RSEXEC server process at the proper host that causes it to execute the ooeration on behalf of the application program The prototype imolementation is incomplete in not all sense However we have successfully run a number of standard application programs including TECO RUNOF «' MACRO LOADER READMAIL and MAILSYS as well as some simole user crograms orototype execution environment ■environment we have been nrograms were that file operations that an application program might initiate are handled TENEX the for which distributed able to For edit examo Te assemble in within load the this and run thi various sour-re files and load nodule files among various hosts in the network without exnlicicly transferrinq files from machine to machine C M nagement of Distributed Data Bases We have iistributed iata base develooed cooies uodating of in a a method for system in this multiple data base in the presence of distributed a manner that -■msistencv of all cooies of the data base ' the reliability maintaining efficiency guarantees the mutual This wotk was motivated reauirements of the TIP login which dictated that the Network User Data Base be maintained manner However we believe -6- that the method has 3GN Reoort 3012 applicability is directly redundant Bolt Beranek and Newman Inc beyond the TIP login system applicable to the task Fcr example the method of maintaininq multiple copies of users' message files as required by the coupled message service The method is completely requires distributed in the sense that it no centralized control nor does it reauire that all copies of the data base be locked simultaneously in order to accomplish the updates The consists method which a is of two parts transmission and distribution described in detail in RFC #677 reliable data independent mechanism which guarantees that all data base updates reach all data base sites and a upd te Pi'iC dure commands stamping sufficient ortermine arrive schema Poi ion how t update data dependent which is activated at data base sites when update The update which of procedure enables the data time consistently makes base seauence incorporate command into their copies -7- use of a time sites to regenerate a of a update events particular to update BBN Report 3012 III Bolt Becanek -_rr Newman Inc TENEX Related Activities A Protocol Development 1 PDP-11 internet Prototype We are currently engaged in network protocol research which is investigating the protocol proposed by Kahn and Ce f A Protocol for InternetwcKK Communication IEEE Transactions on Communications May 1974 for host-to-host different networkb Report 2670 systems across orintor This eventuallv Our first experiment was a provides reliable communication between hosts on the same or this area see BBN verv simplified subset of this protocol which transmission the in ARPANET orotocol comoleted is of to listings a PDP-li remarkably correctlv in from spite tour which drives the line robust of BBN-TENEX listings are a temporary service interruption on TENEX on the PDP-11 or both The use of this orogLam brought to light a serious flaw in current ARi MMET host-IMP protocol The PDP-li input buffers are filled by network messages much faster than the 900 lines minute can empty them so unresnopsive in taking messages from the IM no The source IMP attached to the lineprinter driver the PDP-11 becomes quite once its TENEX buffers system network until fill which transmitting the listing refuses to allow any more traffic to the the is enter previous messages are successful y delivered to the destination PDP-11 This refusal to accept traffic is -8- done by BN Report 3012 locking up Bolt Beranek aid Newman Inc the interface from TENKX to its IMP JO all outgoing traffic to other hosts and TIPs onlv proceeds intervals of tens of seconds in small sourts at This level of service is intolerable to TIP users of that TENEX system The buffer overflow problem occurs in the PDP-11 because the Internet orotocol only performs flow control for buffers in the user space which have been allocated to Internet connections level the IMP inout driver of the operatinq system receive buffers shared these among all incoming network t a lower are a set of aoolications buffers are not under control of the Internet connection flow control The observed oroblem attemots by different was due TENEX systems to multiple simultaneous to establish connections to the PDP-11 the roouests overflowed the receive buffers The cure to the oroblem of the blocked source host interface is i modification to the host-IMP orotocol to permit blocking outgoing traffic to some unresponsive destination with traffic can accepting to other all unresponsive time another destinations traffic and destination message can This reporting were be be interference to done by the IMP's to the not successfully transmitted Each acceoted that no for messsages the cnresoonsive destination the IMP can give the host an explicit qo-ahead -9- BRN Heoort 3012 Bolt Beranek and Newman Inc Until the qenera solution desci ibed above can be imolemented we are forced to the temporar expedient of makinq the PDP-11 alway tesponsive by having its IMP input routine Messages when accept and orotocol detected an away its input buffers are fullr resulting in hundreds of lost messages oer day between TENEX and the PDP-11 Internet throw The prototyoe is so robust that these lost messages are always ret-ansmitted the listings are oerfect in spite c the lossv channel which now exists between t'ENßX and the PDP-11 2 TENEX Internet Experiment During th s quarter control protocol TCP codin of a TCP for TEKSX nuarter ended aitial the soeci f icc't ion for the were of internetwork substantially checkout Li cni n ss ion the experiment and the ccicleted s the of the code was underway and had demonstrated Jelivery of data in several test cases The TCP implementation for TENEX is being utilizing separate virtual job machine to include in user mode the TCP orimitives A holds the main body of the TCP vith communication via shared memory and interrunts with the JSYS running in fSYS trap mechanism see 3 N Peoort 2721 to augment the the user's done the user's job trap interface program The TCP uses the network raw message racility to transmit and tOxdive messages on the ARPA net The TCP is being ro -d in BCPL with the exception of covers which ate code soeed It is expected that the code will the data in machine language to provide additional -10- be transferable 'co the BBN Report 3012 PDP-11 without ßolt Beranek and Newman Inc major re-write The principal obstacles to such a ir ve are the need for double precision arithmetic number manioulations on the PDP-11 in since the these sequence are 32-bit quantities and a different user interface 3 TELNET RCTE TEIiNF T RCTE utilization of is tie a protocol ARPA which permits 5cLJcient more network for terminal 10 by al 'owinc fTiOre characters to be packed into each message and eliminatina most characters from beinq transmitted over the network implementation of TELNET RCTE Remote Echoinq in the Con olled echo The initial Transmission and TENEX T LNFIT user an server was completed during this n u a r t e r This i r olementat ion uncovered two problems in the its input srer i fi cat ion a The sender must buffer transfer its bufferload whenever overflows this means that the receiver must be prepared to receive data even before xt turns the line around to inout reauest This complication w s not explicitly spelled out in the speci fication b in ord t to provide interrupt characters which immediately ev n when ' ere has been tvpeahead the sender ust send it buffer whtnover a break character from take the -11- j effect previously 3N Reoort 3012 specified Bolt Beranek and Newman Inc break set is typed in Th s UIUSL be done even if the receiver has not yet turned the line around Of course the receiver to reouest input must also declare any such interrupt characters to be break characters as well This complication was not explicitly spelled out in the specification a RCTE Implementation In order to make the most etiic'ent use of local echoing of most terminal inout under direction of the remote host a few changes in the wakeup and echoinq loqic of TENEX were necessary A new echo rr ode viz echo non-wakeup characters and do not echo wakeup characters was defined and the assignments of four control characters to wakeup sets were changed mode has been implemented but the change in wakeup The new echo assignments has not yet been made The first attemot at an implementation of RCTÜ in the and Server TELNETs Unfortunatelv relating to awaiting in the a point When the break protocol interrupt TENEX appeared to work fairly well it was discovered that it had a major a snecification on not User explicitly TELNET »as User deficiency addressed blocked on in the input reset from the foreign host there is no way as character orocessor analogously defined to get to and to the control-C -12- force transmission attention literally of the including of on remote TENEX's 8BN Reoort 3012 Bolt Beranek and Newman Inc To solve tbic problem it was necessary to imolement a more comolicated input from transmit its desiqn in which the User TELNET must nrocess terminal even when break-r jset-blocked ind when a RCTE break character is input even if blocked If blocked echoinq it must Similarly also the buffer Server receive input at all times reset much not the cheacters TELNET just must after for lacer be oreoared to sending a break This scheme asynchronous on several levels is complex but apoears to be the only way to solve the problem of being able to send an interrupt character at all times The second-q ne ation imolemenzation described complete is but untested for the User TELNET and not yet complete for the Server survey above of TENEX As an adjunct to software impro' 'i nq the efficiency operation has of been this RCTE imnlementation a begun toward the goal of software relative tc RCTE usinq the smallest necessary wakeuo sets to minimize packets transmitted possible the Included standardization of is a survey interactive directed toward control-character editing conventions b Documentation The documentation of User TELNET la the Use» Guide and the program's own Helo conjunction with this similar file effort was expanded a describe ani updated command In feature to that in RSEXEC was aided to User TELNET to make it -13- BBN Report 3012 ßolt Beranek and Newman Inc easier tor the user to learn the use of the proqram and to keep up with new featuies c Other Changes To improve efficiency ani loqic of reduce security problems the typescript files produced by TELNET has been changed The oroqram ow assigns no typescript file commanded to do so specifically Mso when the default temoorary typescript file is called for it is connected unless directory so created that in it the user's LOGIN not will always be expunged at LOGOUT A new command take input stream from file has been tr allow canned input from a file added rather than from the controlling terminal to be fed to a given remote connection A new comiPc id auto switch to act ive connection added been to invoke a state in which several remote connections can be monitored for state has if a presumably current occasional connection is activity In this inactive for ö set time TELNET hunts for another connection which is active if one is found TELNET switches to that connection 4 PCP Modules tor Navional Software Works Toward orticioation the in end of this Quarter we the National Software Works -14- began our NSW proiect active Since BBN Report 3012 Bolt Beranek and Newman Inc the NSW had been an active effort elsewhere for a number orior to our rarMcipation cur of months initial efforts involv d becoming familiar with the qoais and documented work of the NSW o date attempting to clarify our rolp in the oroject as a whole result of this inspection we have determined that BBN's role and As a shall include the design and imolementation of the strategies and programs necessarv to mal« e BBN TENEX a cool bearing host to the NSW These tasks include building modules to handle the Procedure Call Protocol PCP initial oarkaqe make connection and process dispatching and the modified NSW file package both old environment and Our new commitment tools is run the NSW NVT as well as attempting to correc ly in the NSW based or the assumption that SRI vill provide us with a worKino TENEX PCP imolementation to support the nej ssary NSW packages Another generation result of a set of our of initial evaluation has the orocess of our comments regarding the effectiveness and understandabi1itv of the SRI NSW protocol documentation in been distributing these community -15- observations We are now -o the NSW BBN Report 3012 B Bolt Reranek and Newman Inc Secur ty Cijns 1 The ' ♦-eate Job system call is an imoortant f or two security-related ourposes First addition to corroctinq TENEX errors in access hecks made by previous mechanisms in the system and second movinq some service processes outside the security kernel of TENEX A third purpose is related to the Distributed Computation effort the so-called double loqin problem The CRJOB necessarily JSYS a allows orivileqed one proress system typically backqround service wholly separate job at the reauest of a user nave no oxistina accountinq the created mechanisms job not to create a The created job privileges oevond that of the reauest inq user for services consumed bv but will be will Accounti nq done by the Since the created job is logged in as the requesting user the charges will be properly credited The urcssat state of implementation of CRJOB allows the backqround t sks tne auiojobs to be logged in as unprivileged users for the cases which do ox -i i 1 - of this is the RSEXFC-receivod qrineii Network Control Center iOt reouiro GRIPEWATCH which is special function provided bv privileges the of CltJOB reporte- 3BN--TFNEX to An of the Previously this job ran as a needlesslv privileged orocess adding code to the TENEX securitv use system kernel The in this way renuired addition of an extra entry into r he TENEX r XEC -16- BBN Report 3012 Bolt Beranfk and Newman Inc Purthec work will be required to accomolish the same the qoal for pcr-user incarnations of the File Transfer Protocol server and for the double-loqin task of the TIP and RSEXEC 2 The SECURE terminal program One possible breach of security which has lonq been is the unauthorized unattended by a user -j e of a terminal which recoqnized is left loqqed in and This is especially a problem if the user is a system ooerator or other privileqed person As a stopqap measure a short proqra called SECURE was written to lock up the terminal while it is lefi unattended This proqram additional KEY requests It Lien both the intercepts user's all characters from the terminal until the KEY is KF Y and password are not echoed unauthorized tamoerinq thereby password tvpein and entered and an interrupt aqain The This protects the user's job from preventinq misuse of the user's or ivileqes 0' course if the terminal command lanquaqe is still taken away but the privileqed is connected throuqh a TL0 the TIP active and the terminal it lf jan be «ob ua not -17- ÖBN Report 3012 3 Bolt Beranek and Newman Inc UL1ST The operations utility program ULIST User list the caoability nasswor s has always hai of producinq a user list with or without the users' This program is reqularly used to list user names with t -ir disk quotas directory numbers and other per-usec parameters Since the oassword legitimate listing nurooses and function has has rarely been used for always been used by malicious users after a security breach has occurred cni function has been removed from the ULIST program 4 Accoi nt Validation in LOGIN As criginally planned the user account verification been moved from u -er code the EXEC into the monitor will helo provide a hiqher level of system unauthorized access to accounts security change has This change preventing The VACCT verify account and GDACC get default account JSYS's have been created this by code to facilitate Several other JSYS's were added to help ma e the user interface co the accounting system somewhat cleaner 5 OPHFN - The Operator Function JSYS A possi'-le source of unreliability ard of has been security violations reduced by the addition of the OPRFN system call oast a number of regular operational functions have been In the performed by the operators through commands to the TENEX MiNI-EXEC and Monitor DDT A'hin these mechanisms are used any erroneous tyoing can -18- have 3BN Report 3012 octentially bolt Beranek and Newman Inc disastrous effects since they oriqinally provided for system debuqqing and the operational functions performed are the repair mechanisms Exanoles of in this way are vaiyinq the memory size available to the system r cyclinq the network control proqram to clear it when needed nd switching from attenr d to unattended operation These and other functions have been made available through « he privileged system call OPRFN which is now used by twenty -iew EXEC language commands Monitor DDT and This reduces the need for the operators the MINI-EXEC We may in fact to remove use ' h s capability from the operacois entirely in the future 6 GPACC Access Check In cooperation with Xerox PARC the GFACC has been installed system call JSYS This allows user programs to determine access to files and directories and is used bv server programs to determine the access of an arbitrary user to a specified file or directory 7 Change Password TENEX 1 34 and EXEC 1 53 support the CHANGE PASSWORD for users In o der to guard against typing errors during inputting of the new password the EXEC was subseauently modified the new password to be typed in twice the command to be successful to command echoing to require Both copies must agree for This method was chosen in preference the new password on the user's terminal due to a belief -19- BBN Report 3012 Bolt Beranek and Newman Inc that passwords should never appear even on operator terminals in Durinq this quarter version 1 33 of Tenex was distributed It orinted form C Distribution of TENKX Version 1 33 included the followinq enhancements 1 Pie-slice scheduler The pie-slice scheduler provides a mechanism whereby Tenex jobs ire mappod into service groups oie-slice groups erxh qroup beinq guaranteed a minimum instantaneous service-level determined by svstem administrators A iob's qroup is a function of its current account desiqnator the specific mapping is described to the svstem by the system administrators In addition to regulation of instantaneous service svstem also nrovides for cost-effectiveness by portion factor luarantee loqjed-in the K guarantees jobs r3nresented group or long-term assiqninq made -- an 0 to Setting this of the qrouo administratwelv-determired K groups windfall regulation level to factor 1 of unclaimed service for which there the least cost-effective to 1 provides are no ootimal eaualization of long-term group cost-effectiveness The pie-slice scheduler is cunentiv in operation at BBN on all -20- BBN Report 3012 four systems goals Bolt Beranek and Newman Inc and has been demonstrated to meet its primery desiqn includinq that of performing its increase in at virtjallv no scheduling overhead as compared to the non-pie-slicinq version of the Tenex scheduler as function It is still being refined however its behavior under varying conditions becomes better understood JSYS s tj obtain information sbout the pie-slice aö ied A briei were also description of each of these JbYS's follows CGRP available to wheels and operators onlv pie-slice system allows a user to change to nioup while continuing to charge the same account ATGRP will convert an account to the corresponding pie-slice group This is used in several places by the monitor GPSGN returns the oie-slice grouo that a given job is running in at the current GACTJ does the same except that it returns the account of the job CACCT was also modified changed time without the For privileged users the account pie-slice group clso being chaiged can be Tnis was necessary to keep the printer job operating at a reasonable level of service It is also possible to do a CACCT without it being logged on the logging teletype This will help avoid congestion caused the printer job constantly changing accounts -21- by B8N Report 3012 2 Bolt Beranek and Newman Inc Multi-oack disk swapping Multi-pack disk swapping reorganizes the disk swap area Uvidinq the space equally among the center cylinders of each of the available disk drives as opposed to contiguous area on a single drive areas minimizes reauests with average many operations and with simultaneous arm devices certain rotational allocating the space in The central location of the swap excursion makes servicing possible controllers positioning and simultaneous e g Prior swapping 3339 to installing page-wait los» time to less than 10% under heavy load the advent of multi-pack swapping the even in 192K system became seek equivalent feature BBN's lyscem C was swap-limited in 256K we were unable ceduce a tnis to With cpu-limited Measuiement of the time required to read a page while swapoinq on 5 Calcomp CD230 drives averages approximatelv 27 ms under moderate load this is Queuing delay plus actual service time This compares favorably with 22 ms be for the Bryant drum oerforming more such measurements We will in varying configurations in the near future 3 Non-resident lock conflict strategy Non-resident locks such as directory locks present a in TCNEX because a orocess failing to problem lock such a lock cannot provide the Scheduler with explicit wake-up criteria such as a test of th state of the lock itself because in general references to non-resident storage are not permissible in -22- the scheduler context BBN Report 3012 job and Bolt iSeranek and Newman Inc process-private storage under special circumstances by setting up a is not oven addressable except In the past this difficulty was short-dismiss followed by lock-retry loop problem with this open-loop approach is involved in a process oaqer traps and swaps observed the In fact lockups have occasionally consuming such inordinate was unable to obtain sufficient to complete the sensitive routine and release the lock in a reasonable amount of time single resident The new strategy simply involves the use flag which is set by any process failing to lock any non-resident lock the set state indicates that at one bee i of processor time in the dismiss-wakeup-retry sequence that service a overhead due to many processes attempting to simultaneously seize a tne process possessing the lock of considerable The wakeup usually including at least several single popular non-resident lock and amounts met conflict remains unresolved The failing least process then dismisses itself telling the scheduler to wake it when the flag cleared resident the flag though non-resident lock is testable the lock is on which a by the not conflict scheduler Any because it is process has unlocking occurred this detectable from the value of tne lock itself clears the flag simple wakeups algorithm failing eliminates only when the vast conflicts majority involve processes either on the same or different locks -23- is of more a is This unnecessary than two 112 BBN Rcpor 4 Bolt Beranek and Newman Inc N v ' balance set holding strategy It has been observed that certain processes notaoly the Network POOL Control Program and these processes In the past a removed from the balance-r 3t scheduler collection immediately the the Question qarbage would dismissed contributing is dismissed process was he set of sjhedulable processes by subjecting collector its avoids referenced by members of the balance set in This tend to dismiss themselves freauencly for relatively short intervals the processes running taoes exoerience service and tend to degrade total system performance because TEMEX pages pages to qarbage being actively Upon wakeup the process have to fault back any needed pages lost during interval experiencing to total paging traffic jnv process which dismisses for an delays and overhead and The 1 33 scheduler now notes interval less than a fixed system-global value currently 10ß ms and holds that orocess in the balance set for a oeriod not subsequent dismisses This exceeds the threshold value the working exceeding that value following all continues until a period of dismissal The PurPOse is of course to protect sets of sici dismissed processes on the evidence that the process is likely to awcisen soon at Xeiox PARC This change has been observed to produce a notable reduction in paging traffic -24- BBN Report 3012 D Bolt Beranek and Newman inc BCPL 1 PDP-10 Compiler During generators the was preceding written quarter a new set of P9P-10 code These code generators were written to run with the same parser as the FDP-il compiler This quarter we continued work on these make them that order to generators to fully functional and tj realize a 10 to 20% increase in compiled code efficiency decided code the make After studying tire program need it both more easily the compiler it was careful re-organization in modified and more easily transported A set of header files which describe all of the structures r eated single data lexemes globals and implementation constants has been The ooerator precedence scheme has been easily tree-building testinv- compiler modified table and the isolated entire CAR phases nave been re-written and into parser » re a and undergoing The tree-walking jode-ger erator phases have been examined and the tree walking TRN phase has been re-coded to make use of the structure capabilities of BCPL 2 BDDT BDDT is a source level symbolic debugger for BCPL to fixing several bugs in BDDT -25- In addition a new experimental version was 9BN Report 3012 Bolt Beranek and Newman Inc developed which enables users with all uppercase terminals to programs which use both upper and lower case letters debuq This version needs further work before it is ready to be released 3 PDP-11 BCPL Cross-comoiler Further work on the PDP-11 BCPL cross-compiler was performed in this quarter cannot to resolve decrease the conflictinq number of cases where the compiler reqist r abortion of the computation requirements of in The register use optimizer attempts to select the order of evaluation of operands in order tc number resultinq minimize the extraneous moves either in settinq up the operands or in utilizinq the result operator is order is done The procedure is considered solely only on the once sub-optimal in that each and the decision on evaluation basis of the reqister usaqe in evaluating each ooerand This results in a procedure whose cost in compilation time linearly qrows with the involved rather than one which qrows as 2 N' -26- number of operators BBN Report 3012 IV Bolt Beranek and Newman Inc COTCO Activities A Background As an initial part of the effort to consolidate on Cahu NAVELEX ARPANET-supported existing is considering interactive record message communication systerrs communications experimental services to use of supplement CINCPAC and NAVY personnel will evaluate the applicability of specific and general capabilities for possible use in the final COTCO system described below provide support for the planning such a teot using particular we facilities v ill existing adapt and The and execution ARPANET message technoloa enhance current ARPANET military test use o provide for enhanced reliability meaningful test can be conducted also be In message useful necessary The system cnanqes described will upgrade the existing message capabilities to a level suitable for and of for such a test including appropriate modifications and additions to current message computer support systems for activities The in the test order to assure that a improvements planned wil to the new message software being developed at ISI through the provision of needed system support features The ARPA sponsored work in message systems is currently being strdied by a Message Service Committee with tepiesentatives from the relevant organizations in the ARPA community include institute BBN of Bolt Beranek Technology and Newman Dynamic These MIT-DMS Modjlling -27- organizations Massachusetts Systems SRI-ARC BQN Report 3012 Stanford USC-ISI Research Institute University Institute 1 Boxt Beranek and Newman Inc of Augmentation Southern Research California Center and Information Sciences ARPA Has tasked this committee with Identifying possible requirements future message services for current and within DoD as well as the ARPA research community 2 Identifying the computer science issues and research problems that must be solved to meet these reauiiements 3 Evaluating systems current with ARPA respect to R D efforts on applicability message to these services 4 Generating short term intermediate term and long term plans for meeting the identified objectives The recommendations generated for ARPA by the Committee should prove helpful and illuminating reauirements for a direct writer-to-reader service -28- Message Servi ce in identifying OBN Report 3012 Bolt Beranok and Newman Inc The existing ARPANET message service development were by the responsible opeiating ARPANET system This been in continuous community for the last two years de ei ■»ping for has these ii servic services provided on by the SNDMSG The message-creator is interactive editor program a special which compose the text of his message and a specifies subject addresses etc the message be sent a action purpose helps Once the writer is a writer header addressees which information satisfied with he gives a command for the message to At this point the message-creator copy of the message queues for background-mode a system-provided transmission to each addressee 2 MAILER The background outgoing message-sender job which message is periodically queues surveys written the by the message-creator The message-sender is responsible for each transmitting addressed queued destination and message removing to its each message from the queue after its receiot has been positively acknowledged from the transmission takes place protocol called the receiving in the enu ARPANET This using File Transfer Protocol -29- TENEX four different program modules on the host computers of the ARPANET 1 We a FTP 1BN Renort 3012 Bolt B ranek and Newman Inc which provides control and positive acknowledgement for message moving between hosts on the ARPANET 3 P'TPSRV The message-receiver system-provided from ARPANET store other standard transmiLsion to recipient and Once hosts incoming It uses the for control the message-receiver it must dispatch acknowledge ARPANET FTP received a message field another background job which is awakened as needed to receive messages is the of interpret message to message has the address the correct The message is delivered by appending it to the addressee's message-file 4 MAILSYS orogram The message-read r module invoked is by message-file surveying all header It received provides received messages fields of selected messages messages facilities in for display of selected reading the messages combination on his terminal interactive a message recipient to assist him in processing the his an in any order or and oroducing hard copy It also permits the recipient to dispose of messages by deleting them or appending them tc retrieval messages other The from files of message his reader these other choice will for later retrieve files in the same way it -30- BBN Report 3012 Bolt Be'-onek ar d Newman Inc retrieves messages from his messaqe-file permittinq selective retrieval or a number primitive of based on author other cataloged keys This information subject date constitutes a storaqe retrieval faci1ity B Project Activities Durirq calendar modifications an H 1975 we extensions facilities on the ARPANET to message processing specific modifications responsiveness human These software orovide header fields software system will and functions and implement Existinq messaqe enqineerinq chanqes in tect-system for MAVY DoD software requires service relicbility qenerality and existinq messaqe the accounting service such things as approoriate military Message Changes in the supporting system correct known minor deficiencies and improve overall value general or other a improve formats reliability continuing sunport to desiqn to existinq wriUer-to-readei message requirements capabilities will will in The result of our efforts should have that the system enhancement will be useful applications will form a basis for and many of the message in service further extension by others such as ISI We started this activity in January 1975 and plan to have usable initial message system available in first quarter 1975 initial system which will contain only -31- minor changes from a This the n3N Report 3012 Bolt Beranek and Newman Inc current systemr to enhance reliability and other critical aspects of the system w 11 be evaluated by NAVI'LEX for utilizing such will then complete reauirements issues generated a system for the experimental test-system any relevant discovered involved A plan will be and chanqes respond to We additional durinq the evaluation and ir vestiqate the needed developments for meeting long-term reauirements for military message processing Messaqe system proqrams will Compatible Programming currently suooorted on be implemented Lanquaqe a high-level PDP-10'sf PDP-11's in I8M--360's Honeywell At some future iate it may be necessary or desirable to transport into Basic lanquage which is 6i 80's# and an assortment of other popular machines functions BCPL message system other machines and our BCPL structure will greatly ■Mi this process Our efforts will adapt the existing message services to the military environment and formats and provide additional capabilities in the support systems needed for the test The current ARPANET interactive message service is a promising basis which can be molded into a suitable test-system economically and rapidly existing By adapting and proven software and by using already existing hardware and communication facilities an initial test can low cost and on a rapid time scale -32- be conducted at I PRN Report 301 C Bolt Beianek ana Newman Inc MAILSYS A firsc Processinq experimental System was version out into of the M new operation ML SYS Message the previous quarter After a period of testing ar J refinement the new system was released for BBN ENEX users in January 1975 This first version of MAILSYS provides message management services for incoming mail contains commands for manipulating The system 'in-box and other message files It is possible to survey the contents of a message file to perform selective retrieval on stored messages to delete unwanted messages and to move messages rrom mechanisms possible make it c one l to combinution of message field that retrievals can uo another The retrieval extract complete messaies or anv rhe user may wish Selective filter on the contents of various message fields such as author date addressees or subject Message creation in this first version of MAILSYS is handled by invoking the feature with in'erioi - standard FNDMSG program from within MAILSYS very general Executive power- System is This the ability permits c ovinq and other manipulation not directly to for Anothtr invoke a example file for the provided in MAILSYS code Since the January release substantial progress has on a new and more powerful version of MAILSYS version is nearing completion and its release is near future -33- been made Work on the new expected in the BBN Report 3012 Bolt Beranek and Newcan Inc r s far as a user ii concerned» the most the new to invo'-e SNDMSG fields It will permit the user in any order he wishes specified fields as often as desired The of The new creation facility will be command driven rather than having the dialogue format of SNDMSG messaqe featu • system will be the ability to create and transmit messages from within MAILSYS without the need messaqe important user need to specify and to return to previously for editing or replacement not transmit the mesoage until he is satisfied with its entire contents h second change of direct significance to the user is the ability to treat a message retrieval filter as an obiect which can be used repeatedly and incrementally changed during a session with MAILSYS The new version of incremental version reauested MAILSYS will also contain a series of changes improvements and extensions beyond the present They account tor almost by users and olanned half for of all eventual changes currently implementation in MAILSYS i -34- BBN Report 3012 D Bolt Beranek and Newman Inc DOCUMENTATION An initial user guide was released with the January version MAILSYS Work is of under way on a revised version of this document which describes the February MAILSYS release The second type of built into MAILF user documentation consists of commands that provide explanatory assistance to the user Initial versions of these c - mands were implemented in release of MAILSYS These the January are now in process of update and new versions will be available along with the next MAILSYS release E MAILER and FTPSRV The project calls for modification to these underlying programs in order to support evolving MAILSYS system and enhance service the operation of the The majority of these t'jsks are intended to render the operation of MAILSYS more efficient and to provide for enhanced security completed During the current reporting period we have modifications to MAILER which provide for the delivery of local message items through the PTPSRV subsystem Modifications to FTPSRV provide for Queuing of incoming messages when the destination inbox is busy F TENEX Capabilities In addition to MAILER and FTPSRV efficient safe operation of the new MAILSYS calls -35- for and secure certain changes in the BBN Report 3012 Bolt Beranek and Newman Inc underlying TENEX operating system made in the TENEX accounting orocessing services to be number charged A basic system to modification that the will user 's has been permit message logged in job Formerly L certain portion of these were chanued to system overhead jobs -36-