From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=0.1 required=5.0 tests=BAYES_05,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,1356f4179c1e4ef4 X-Google-Attributes: gid103376,public From: "Samuel T. Harris" Subject: Re: ADA task Date: 1996/09/16 Message-ID: <323D820C.59E2@gsde.hso.link.com>#1/1 X-Deja-AN: 180928785 references: <5174qu$o1p@nr1.ottawa.istar.net> <51cjp0$q7k@watnews1.watson.ibm.com> <323A1FF2.2781@gsde.hso.link.com> <323B1F23.2781@gsde.hso.link.com> <01bba2f7$aa439c00$3c8371a5@dhoossr.iquest.com> content-type: text/plain; charset=us-ascii organization: Hughes Training Inc. - Houston Operations mime-version: 1.0 newsgroups: comp.lang.ada x-mailer: Mozilla 3.0 (X11; I; IRIX 5.3 IP19) Date: 1996-09-16T00:00:00+00:00 List-Id: David C. Hoos, Sr. wrote: > > You're right about VADS on SGI "out of the box". However, we (Hughes > Aircraft -- Huntsville, AL) run our process which needs higher-fidelity > delays at non-degrading priority 39 (IRIX 5 & 6), with the fast_Hz clock > set to 2 KHz. You may also need to change v_usr_conf_b.a (I don't remember > off the top of my head) to reduce that 10 ms. fudge factor to 0. We have > found worst-case infidelity of 2-3 ms. on a heavily-loaded (development) > machine, but typically under 500 micro-sec., as would be expected. The Ada > run time gets to check for expired delays usually every 500 micro-sec. > Normally to get priority 39, you have to run with super-user privileges, > but we reconfigured the kernel to allow just the one priority level (the > lowest level using the Fast_Hz clock instead of the 10 ms. sginap) to be > run by users. Since most don't care enough to find out how to run at that > priority, generally only the "official" executables needing RT priority run > this way. > -- Except for the requirement to be super-user and the limitations on priority levels, that is a good way to "configure" VADS to meet the need. Some folks might find the limitations a problem but it seems to work for you. For us, the clock driven approach is best since we MUST stay in sync with other distributed session hosts. All simulation assets are driven by a central GPS coordinated CTE clock setup. As a side note related to another thread, the package v_usr_conf_b.a is also were one would place a custom heap memory manager, perhaps with garbage collection (which is being discussed elsewhere in the group). -- Samuel T. Harris, Senior Engineer Hughes Training, Inc. - Houston Operations 2224 Bay Area Blvd. Houston, TX 77058-2099 "If you can make it, We can fake it!"