Re: SV: Mersenne: number of processors participating
On Tue, 30 Oct 2001 21:33:59 -0500, Rick Pali [EMAIL PROTECTED] wrote: Aaron Blosser wrote: Good old sysinternals... they have the neatest tools. Damn straight! I've been using (and loving) PageDefrag since I stumbled on that site. A few other gems have since made their way onto my system... Rick. See also HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\ClearPageFileAtShutdown This setting was put in place by a 'twink' program I tried a month or two back, and has been working great for me (marginally more secure too). Nathan _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: SV: Mersenne: number of processors participating
Another other way to fix the problem is to have the compute- intensive process voluntarily relinquish its timeslice at intervals which are much shorter than the minimum timeslice (which is typically of the order of 200 ms). This reduces the efficiency of the compute-intensive task to some extent but does make it coexist better. I suppose it would be possible to build this into Prime95; if this is done I would like options to be multimedia friendly or optimally efficient - probably the best way to implement would be to have the code contain the relevant system calls but to NOOP over them if efficiency is demanded. I've made good experience with throwing a sched_yield() into the MFAC code. The machines MFAC was running on had a Linux 2.4 kernel which gives even niceness 19 process about 10% cpu when another normal niceness process is running, which some users complained about. I wasn't particularly careful where I put the sched_yield(), I think it was called far more often than neccesary (many times/ms) but the effect on performance was not that dramatic - about 5% slowdown. The overhead in the scheduler seems to be pretty low. With that, when another process was running, MFAC worked at about 1/1000 the normal speed, so it must have gotten less than 0.1 % cpu time. Users were happy again. Perhaps the performance loss can be reduced by placing the yield somewhere in the code where the data currently in cache is finished and new data must be read from memory. If another process wants to run, at least it'll throw data out of the cache that we dont need anymore anyways (let some other job do our dirty flushing). Alex _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: SV: Mersenne: number of processors participating
On 30 Oct 2001, at 14:39, John R Pierce wrote: near as I can guess, the issue here is that Prime95 is running a few priority notches above idle and when another process tries to run at a lower priority it will stall behind prime95. Well - a process that keeps being preempted will tend to rise in priority a process that keeps preempting will tend to fall (unless it's running at real time priority) - so that might explain it. Reducing the timeslice would still help in the steady state when continuous heavy I/O is occurring, by reducing the proportion of the time the compute-intensive process has the CPU. Regards Brian Beesley _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: SV: Mersenne: number of processors participating
On 29 Oct 2001, at 19:37, John R Pierce wrote: I've had similar problems with a few other multimedia sorts of junkware. Near as I can tell, some of these things put their video or animation thread at Idle_Priority+1 or something, and it gets eaten alive by Prime95. Isn't it the old problem - no matter what priority a process is running at, unless it's interrupt driven it won't preempt a process running at a lower priority. The problem here is that the multimedia stuff wants to do a very little work but very often. It gets slowed down because Prime95 hangs on to the processor until its timeslice expires - it almost never has to wait for some external event. Ideally the multimedia stuff would be driven by timer interrupt. But for some reason (maybe something to do with there being a limited number of timer channels, and those having rather poor resolution) this approach seems to be quite rare on PC systems. One way to improve the performance in these circumstances is to reduce the minimum timeslice for low-priority processes. This will cause the task scheduler to be busier and therefore reduce the overall performance to some extent, but multimedia type applications will coexist much more happily with compute-intensive tasks if this is done. Sorry, I have no idea how to do this, or even whether it is possible, in any of the versions of Windows. The linux 2.4 kernel does this almost automatically, by having a much smaller minimum timeslice for idle-priority processes than for processes running above idle priority. (The timeslice is reduced again for processes running at unusually high priority, so that they can't hog the whole system quite so easily.) I believe the timeslice parameters are tunable (without having to recompile the kernel), but I have no personal experience of actually doing this. Another other way to fix the problem is to have the compute- intensive process voluntarily relinquish its timeslice at intervals which are much shorter than the minimum timeslice (which is typically of the order of 200 ms). This reduces the efficiency of the compute-intensive task to some extent but does make it coexist better. I suppose it would be possible to build this into Prime95; if this is done I would like options to be multimedia friendly or optimally efficient - probably the best way to implement would be to have the code contain the relevant system calls but to NOOP over them if efficiency is demanded. The remaining problem with this approach is that how often you would want to make these system calls would depend very heavily on the processor speed. Relinquishing the timeslice very frequently would enable even slow systems to run multimedia pretty seamlessly, but at a heavy cost on all systems. Placing the system calls in a position where they would be effective but not too costly, across a large range of processor speeds and a large range of FFT run lengths, would not be a trivial task. Regards Brian Beesley _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: SV: Mersenne: number of processors participating
I've had similar problems with a few other multimedia sorts of junkware. Near as I can tell, some of these things put their video or animation thread at Idle_Priority+1 or something, and it gets eaten alive by Prime95. Isn't it the old problem - no matter what priority a process is running at, unless it's interrupt driven it won't preempt a process running at a lower priority. ... process and thread dispatching in MS Windows IS interrupt driven. Anything that causes a thread or process thats waiting to become ready will cause it to immediately dispatch if its the highest priority ready process, the system doesn't wait for the next major quantum tick. Multimedia stuff is either waiting on sound buffer events, or multimedia timer events (which have 1mS resolution) or disk IO buffer events, or software semaphore events, all of which are interrupt driven and will cause an immediate dispatch. near as I can guess, the issue here is that Prime95 is running a few priority notches above idle and when another process tries to run at a lower priority it will stall behind prime95. _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
RE: SV: Mersenne: number of processors participating
One way to improve the performance in these circumstances is to reduce the minimum timeslice for low-priority processes. This will cause the task scheduler to be busier and therefore reduce the overall performance to some extent, but multimedia type applications will coexist much more happily with compute-intensive tasks if this is done. Sorry, I have no idea how to do this, or even whether it is possible, in any of the versions of Windows. There is a program that can set the quanta for programs... let me find that durned thing... Aha. http://www.sysinternals.com/ntw2k/freeware/frob.shtml Good old sysinternals... they have the neatest tools. Apparently that's just for NT4 machines (I think...). For Win2K (and presumably XP?), they have another page that tells you about the settings on there, and to wait for a new version of Frob that works with win2k. http://www.sysinternals.com/ntw2k/info/nt5.shtml Aaron _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
SV: SV: Mersenne: number of processors participating
Ups, by help from Brian Beesley and a little work with the time= I have it working now. I think it was my old paranoia from a time when I was not running the servers alone - I wouldn't let anyone know that a program like prime95 was active. Now I don't care as I have nobody but users to face. Thanks to all. Happy hunting tsc -Oprindelig meddelelse- Fra: George Woltman Sendt: ma 29-10-2001 22:47 Til: Torben Schlüntz Cc: Emne: Re: SV: Mersenne: number of processors participating Hi, At 10:01 PM 10/29/2001 +0100, you wrote: I would like to use the servers; but I haven't been able to persuade George to make a Quit function like quit_at: 06:00 to terminate the program when users arrives and optimum performance is needed Look in readme.txt for the Time= entry in prime.ini This feature can be used to make prime95 go dormant at a specified time. Hope that helps, George _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
RE: SV: Mersenne: number of processors participating
Aaron Blosser wrote: Good old sysinternals... they have the neatest tools. Damn straight! I've been using (and loving) PageDefrag since I stumbled on that site. A few other gems have since made their way onto my system... Rick. -+--- [EMAIL PROTECTED] http://www.alienshore.com/seeking/ _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Thrashing (was Re: SV: Mersenne: number of processors participating)
What will really slow a workstation or server down is running short of RAM. These days the working sets are getting appreciable as the exponents increase. NT scheduling will wake up the service version of ntprime every second I think and give it at least one quantum. If some more essential service or application needs nearly all available RAM for its working set, and the working set of ntprime is big enough it gets paged out, the disk thrashes wildly and performance can suffer greatly for both the ntprime service and the other service or application, even while the ntprime service only gets a percent or two of cpu time. This is not just a characteristic of NT, but a general property of virtual memory operating systems; eventually it's just too little ram or too much demand, leading to performance decline. Ken At 05:05 PM 10/29/2001 -0800, Aaron Blosser wrote: Still the only time I've ever seen Prime95/NTPrime slow down a system is when I was doing some Netmeeting video conferences. _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
SV: Mersenne: number of processors participating
I admit I'm not that good in telling primenet what computers I have and what throughput rate to expect. eg.: I made 14 accounts all using the same 150 Mhz machine, though I knew none or only few would be 150 Mhz. These accounts all run occassionally, eg. in company holiday around the clock, outside of holiday more random. Over time I have been wiser to use more power of those machines staying awake all night anyway. :-) I would like to use the servers; but I haven't been able to persuade George to make a Quit function like quit_at: 06:00 to terminate the program when users arrives and optimum performance is needed (with no question what so ever about serverperformance); And I don't wake up at 6 to turn prime95 or anything else off unless there is a severe error reported by users. Happy hunting tsc -Oprindelig meddelelse- Fra: Henk Stokhorst Sendt: ma 29-10-2001 19:30 Til: Alan Vidmar; [EMAIL PROTECTED] Cc: Emne: Re: Mersenne: number of processors participating Alan Vidmar wrote: I suggest that there be a switch added so that ppl can use Prime95 as a processor test but without ever getting real assignments,... This is a VERY good suggestion. However it has already been implemented in the latest version (v21). That version contains more improvements so I wondered if it wouldn't be a good idea to inform users through the occasional newsletter. Particulary because it gives a 10% improvement for Pentium I, II and III users and it skips P-1 if it has been done. YotN, Henk Stokhorst. PS those abandoned assignments do't slow down the project. They just scatter the work over a larger range. _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
SV: SV: Mersenne: number of processors participating
Yep! But the time entry only allows the program to sleep (still eating all CPU cycles even when running at zero priority). Take any NT 4.0 or W2K machine and you will see the system idle time doesn't add seconds while Prime95 still eats them (and doing nothing). For my servers to become prime95's I need to be sure they only run what I have planned at anytime. I can start Prime95 scheduled. I don't mind! But the users should never have one chance of claiming servers aren't available or even running slow. I know you are certain and I know you gotta be damn good at this (very far beyond anything I will ever manage); but still any doubt will become my users advantage. Make the sleepy nights for my servers glorius. I make them start prime95 by a schedule and You make prime95 die by harikiri - and I decide when everything happens. :-) Tnx in advance. Still happy hunting tsc -Oprindelig meddelelse- Fra: George Woltman Sendt: ma 29-10-2001 22:47 Til: Torben Schlüntz Cc: Emne: Re: SV: Mersenne: number of processors participating Hi, At 10:01 PM 10/29/2001 +0100, you wrote: I would like to use the servers; but I haven't been able to persuade George to make a Quit function like quit_at: 06:00 to terminate the program when users arrives and optimum performance is needed Look in readme.txt for the Time= entry in prime.ini This feature can be used to make prime95 go dormant at a specified time. Hope that helps, George _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: SV: Mersenne: number of processors participating
Still the only time I've ever seen Prime95/NTPrime slow down a system is when I was doing some Netmeeting video conferences. With it running, the video conference would run DOG slow. Stop the NTPrime service and curiously had to restart the video conference for the effect, but the video would then be running great. That was with, umm.. version 20 I think? I haven't tried again with later versions... wasn't one of the things George did something to do with the priority setting? I've had similar problems with a few other multimedia sorts of junkware. Near as I can tell, some of these things put their video or animation thread at Idle_Priority+1 or something, and it gets eaten alive by Prime95. -jrp _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: SV: Mersenne: number of processors participating
On Mon, 29 Oct 2001 17:05:02 -0800, Aaron Blosser [EMAIL PROTECTED] wrote: Still the only time I've ever seen Prime95/NTPrime slow down a system is when I was doing some Netmeeting video conferences. With it running, the video conference would run DOG slow. Stop the NTPrime service and curiously had to restart the video conference for the effect, but the video would then be running great. That was with, umm.. version 20 I think? I haven't tried again with later versions... wasn't one of the things George did something to do with the priority setting? Aaron Out of curiousity, have you tried tinkering with the thread priorities of the programs in question? I find the utility bvslice (http://www.blueneptune.com/~maznliz/marius/software.shtml) to be quite useful. Nathan _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
