|From:||Srivatsa Vaddagiri <email@example.com>|
|To:||firstname.lastname@example.org, Ingo Molnar <email@example.com>, Nick Piggin <firstname.lastname@example.org>, Andrew Morton <email@example.com>|
|Subject:||[RFC] Fair-user scheduler|
|Date:||Fri, 26 Jan 2007 11:31:42 +0530|
Current Linux CPU scheduler doesnt recognize process aggregates while allocating bandwidth. As a result of this, an user could simply spawn large number of processes and get more bandwidth than others. Here's a patch that provides fair allocation for all users in a system. Some benchmark numbers with and without the patch applied follows: user "vatsa" user "guest" (make -s -j4 bzImage) (make -s -j20 bzImage) 2.6.20-rc5 472.07s (real) 257.48s (real) 2.6.20-rc5+fairsched 766.74s (real) 766.73s (real) (Numbers taken on a 2way Intel x86_64 box) Eventually something like this can be extended to do weighted fair share scheduling for: - KVM - containers - resource management Salient features of the patch: - Based on Ingo's RTLIMIT_RT_CPU patch . Primary difference between RTLIMIT_RT_CPU patch and this one is that this patch handles starvation of lower priority tasks in a group and also accounting is token based (rather than decaying avg). - Retains existing one-runqueue-per-cpu design - breaks O(1) (ouch!) Best way to avoid this is to split runqueue to be per-user and per-cpu, which I have not implemented to keep the patch simple. - Fairsched aware SMP load balance NOT addressed (yet) Comments/flames wellcome! References: 1. http://kernel.org/pub/linux/kernel/people/akpm/patches/2.... -- Regards, vatsa
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