Messages in this thread | | | Date | Tue, 28 Aug 2007 23:37:34 -0400 | From | Bill Davidsen <> | Subject | Re: CFS review |
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Al Boldi wrote: > Ingo Molnar wrote: >> * Al Boldi <a1426z@gawab.com> wrote: >>>>> The problem is that consecutive runs don't give consistent results >>>>> and sometimes stalls. You may want to try that. >>>> well, there's a natural saturation point after a few hundred tasks >>>> (depending on your CPU's speed), at which point there's no idle time >>>> left. From that point on things get slower progressively (and the >>>> ability of the shell to start new ping tasks is impacted as well), >>>> but that's expected on an overloaded system, isnt it? >>> Of course, things should get slower with higher load, but it should be >>> consistent without stalls. >>> >>> To see this problem, make sure you boot into /bin/sh with the normal >>> VGA console (ie. not fb-console). Then try each loop a few times to >>> show different behaviour; loops like: >>> >>> # for ((i=0; i<3333; i++)); do ping 10.1 -A > /dev/null & done >>> >>> # for ((i=0; i<3333; i++)); do nice -99 ping 10.1 -A > /dev/null & done >>> >>> # { for ((i=0; i<3333; i++)); do >>> ping 10.1 -A > /dev/null & >>> done } > /dev/null 2>&1 >>> >>> Especially the last one sometimes causes a complete console lock-up, >>> while the other two sometimes stall then surge periodically. >> ok. I think i might finally have found the bug causing this. Could you >> try the fix below, does your webserver thread-startup test work any >> better? > > It seems to help somewhat, but the problem is still visible. Even v20.3 on > 2.6.22.5 didn't help. > > It does look related to ia-boosting, so I turned off __update_curr like Roman > mentioned, which had an enormous smoothing effect, but then nice levels > completely break down and lockup the system. > > There is another way to show the problem visually under X (vesa-driver), by > starting 3 gears simultaneously, which after laying them out side-by-side > need some settling time before smoothing out. Without __update_curr it's > absolutely smooth from the start.
I posted a LOT of stuff using the glitch1 script, and finally found a set of tuning values which make the test script run smooth. See back posts, I don't have them here.
-- Bill Davidsen <davidsen@tmr.com> "We have more to fear from the bungling of the incompetent than from the machinations of the wicked." - from Slashdot - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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