From: Peter Zijlstra <peterz@infradead.org>
To: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>, Mike Galbraith <efault@gmx.de>,
Suresh Siddha <suresh.b.siddha@intel.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Paul Turner <pjt@google.com>
Subject: Re: sched: Avoid SMT siblings in select_idle_sibling() if possible
Date: Mon, 26 Mar 2012 10:29:43 +0200 [thread overview]
Message-ID: <1332750583.16159.79.camel@twins> (raw)
In-Reply-To: <20120322153205.GA28570@linux.vnet.ibm.com>
On Thu, 2012-03-22 at 21:02 +0530, Srivatsa Vaddagiri wrote:
> Anyway, there are degradations as well, considering which I see
> several
> possibilities:
>
> 1. Do balance-on-wake for vcpu threads only.
Hell no ;-) we're not going to special case some threads over others.
> 2. Document tuning possibility to improve performance in virtualized
> environment:
> - Either via sched_domain flags (disable SD_WAKE_AFFINE
> at all levels and enable SD_BALANCE_WAKE at SMT/MC levels)
But domain flags are not exported -- except under SCHED_DEBUG and that
sysctl mess.. also SD_flags are not stable.
> - Or via a new sched_feat(BALANCE_WAKE) tunable
sched_feat() is not a stable ABI and shouldn't ever be used for anything
but debugging (hence it lives in debugfs and goes away if you disable
SCHED_DEBUG).
I would very much like more information on why things are a loss. Is it
really related to what cpu you pick, or is it the cost of doing the
balance thing?
next prev parent reply other threads:[~2012-03-26 8:29 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1329764866.2293.376.camhel@twins>
2012-03-05 15:24 ` sched: Avoid SMT siblings in select_idle_sibling() if possible Srivatsa Vaddagiri
2012-03-06 9:14 ` Ingo Molnar
2012-03-06 10:03 ` Srivatsa Vaddagiri
2012-03-22 15:32 ` Srivatsa Vaddagiri
2012-03-23 6:38 ` Mike Galbraith
2012-03-26 8:29 ` Peter Zijlstra [this message]
2012-03-26 8:36 ` Peter Zijlstra
2012-03-26 17:35 ` Srivatsa Vaddagiri
2012-03-26 18:06 ` Peter Zijlstra
2012-03-27 13:56 ` Mike Galbraith
2011-11-15 9:46 Peter Zijlstra
2011-11-16 1:14 ` Suresh Siddha
2011-11-16 9:24 ` Mike Galbraith
2011-11-16 18:37 ` Suresh Siddha
2011-11-17 1:59 ` Mike Galbraith
2011-11-17 15:38 ` Mike Galbraith
2011-11-17 15:56 ` Peter Zijlstra
2011-11-17 16:38 ` Mike Galbraith
2011-11-17 17:36 ` Suresh Siddha
2011-11-18 15:14 ` Mike Galbraith
2012-02-20 14:41 ` Peter Zijlstra
2012-02-20 15:03 ` Srivatsa Vaddagiri
2012-02-20 18:25 ` Mike Galbraith
2012-02-21 0:06 ` Srivatsa Vaddagiri
2012-02-21 6:37 ` Mike Galbraith
2012-02-21 8:09 ` Srivatsa Vaddagiri
2012-02-20 18:14 ` Mike Galbraith
2012-02-20 18:15 ` Peter Zijlstra
2012-02-20 19:07 ` Peter Zijlstra
2012-02-21 5:43 ` Mike Galbraith
2012-02-21 8:32 ` Srivatsa Vaddagiri
2012-02-21 9:21 ` Mike Galbraith
2012-02-21 10:37 ` Peter Zijlstra
2012-02-21 14:58 ` Srivatsa Vaddagiri
2012-02-23 10:49 ` Srivatsa Vaddagiri
2012-02-23 11:19 ` Ingo Molnar
2012-02-23 12:18 ` Srivatsa Vaddagiri
2012-02-23 11:20 ` Srivatsa Vaddagiri
2012-02-23 11:26 ` Ingo Molnar
2012-02-23 11:32 ` Srivatsa Vaddagiri
2012-02-23 16:17 ` Ingo Molnar
2012-02-23 11:21 ` Mike Galbraith
2012-02-25 6:54 ` Srivatsa Vaddagiri
2012-02-25 8:30 ` Mike Galbraith
2012-02-27 22:11 ` Suresh Siddha
2012-02-28 5:05 ` Mike Galbraith
2011-11-17 19:08 ` Suresh Siddha
2011-11-18 15:12 ` Peter Zijlstra
2011-11-18 15:26 ` Mike Galbraith
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