From: Mala A. <ma...@us...> - 2003-07-29 14:06:47
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>> If you want data supporting my assumptions: Ted Ts'o's talk at OLS >> shows the necessity to rebalance ASAP (even in try_to_wake_up). >If this is the patch I am thinking of, it was the (attached) one I sent them, >which did a light "push" rebalance at try_to_wake_up. Calling load_balance >at try_to_wake_up seems very heavy-weight. This patch only looks for an idle >cpu (within the same node) to wake up on before task activation, only if the >task_rq(p)->nr_running is too long. So, yes, I do believe this can be >important, but I think it's only called for when we have an idle cpu. The patch that you sent to Rajan didn't yield any improvement on specjappserver so we did not include that in the ols paper. What is described in the ols paper is "calling load-balance" from try-to-wake-up. Both calling load-balance from try-to-wakeup and the "light push" rebalance at try_to_wake_up are already done in Andrea's 0(1) scheduler patch. Regards, Mala Mala Anand IBM Linux Technology Center - Kernel Performance E-mail:ma...@us... http://www-124.ibm.com/developerworks/opensource/linuxperf http://www-124.ibm.com/developerworks/projects/linuxperf Phone:838-8088; Tie-line:678-8088 |
From: Mala A. <ma...@us...> - 2003-07-29 17:07:03
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>Are the balances you're doing on wakeup global or node-local? The test is not done on NUMA systems. Regards, Mala Mala Anand IBM Linux Technology Center - Kernel Performance E-mail:ma...@us... http://www-124.ibm.com/developerworks/opensource/linuxperf http://www-124.ibm.com/developerworks/projects/linuxperf Phone:838-8088; Tie-line:678-8088 "Martin J. Bligh" <mb...@ar...> To: Mala Anand/Austin/IBM@IBMUS, Erich Focht <ef...@hp...>, linux-kernel Sent by: <lin...@vg...>, LSE <lse...@li...> lse...@li...ur cc: Andi Kleen <ak...@mu...>, tor...@os... ceforge.net Subject: Re: [Lse-tech] Re: [patch] scheduler fix for 1cpu/node case 07/29/2003 09:29 AM >>> If you want data supporting my assumptions: Ted Ts'o's talk at OLS >>> shows the necessity to rebalance ASAP (even in try_to_wake_up). > >> If this is the patch I am thinking of, it was the (attached) one I sent > them, >> which did a light "push" rebalance at try_to_wake_up. Calling > load_balance >> at try_to_wake_up seems very heavy-weight. This patch only looks for an > idle >> cpu (within the same node) to wake up on before task activation, only if > the >> task_rq(p)->nr_running is too long. So, yes, I do believe this can be >> important, but I think it's only called for when we have an idle cpu. > > The patch that you sent to Rajan didn't yield any improvement on > specjappserver so we did not include that in the ols paper. What > is described in the ols paper is "calling load-balance" from > try-to-wake-up. Both calling load-balance from try-to-wakeup and > the "light push" rebalance at try_to_wake_up are already done in > Andrea's 0(1) scheduler patch. Are the balances you're doing on wakeup global or node-local? M. ------------------------------------------------------- This SF.Net email sponsored by: Free pre-built ASP.NET sites including Data Reports, E-commerce, Portals, and Forums are available now. Download today and enter to win an XBOX or Visual Studio .NET. http://aspnet.click-url.com/go/psa00100003ave/direct;at.aspnet_072303_01/01 _______________________________________________ Lse-tech mailing list Lse...@li... https://lists.sourceforge.net/lists/listinfo/lse-tech |
From: Luck, T. <ton...@in...> - 2003-07-30 16:56:06
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> As for idle balances, we may be able to go a step further:=20 > follow the range rules, but do a more aggressive/frequent search. Be cautious about how much work you do here ... while you can burn as much cpu time as you like on an idle cpu without affecting anything, you need to be sure that your activities don't burn too much bus bandwidth, or cause cache lines to ping-pong around the machine. The classic case of this has been seen while one cpu is trying to boot, and the other 31 idle cpus beat the bus to death looking to see whether they can "help". -Tony |
From: Martin J. B. <mb...@ar...> - 2003-07-29 14:29:42
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>>> If you want data supporting my assumptions: Ted Ts'o's talk at OLS >>> shows the necessity to rebalance ASAP (even in try_to_wake_up). > >> If this is the patch I am thinking of, it was the (attached) one I sent > them, >> which did a light "push" rebalance at try_to_wake_up. Calling > load_balance >> at try_to_wake_up seems very heavy-weight. This patch only looks for an > idle >> cpu (within the same node) to wake up on before task activation, only if > the >> task_rq(p)->nr_running is too long. So, yes, I do believe this can be >> important, but I think it's only called for when we have an idle cpu. > > The patch that you sent to Rajan didn't yield any improvement on > specjappserver so we did not include that in the ols paper. What > is described in the ols paper is "calling load-balance" from > try-to-wake-up. Both calling load-balance from try-to-wakeup and > the "light push" rebalance at try_to_wake_up are already done in > Andrea's 0(1) scheduler patch. Are the balances you're doing on wakeup global or node-local? M. |