From: Peter Zijlstra <peterz@infradead.org>
To: Steven Sistare <steven.sistare@oracle.com>
Cc: subhra mazumdar <subhra.mazumdar@oracle.com>,
linux-kernel@vger.kernel.org, mingo@redhat.com,
dhaval.giani@oracle.com, tim.c.chen@linux.intel.com
Subject: Re: [RESEND RFC PATCH V3] sched: Improve scalability of select_idle_sibling using SMT balance
Date: Mon, 5 Feb 2018 18:03:58 +0100 [thread overview]
Message-ID: <20180205170358.GT2295@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180205124854.GX2269@hirez.programming.kicks-ass.net>
On Mon, Feb 05, 2018 at 01:48:54PM +0100, Peter Zijlstra wrote:
> So while I see the point of tracking these numbers (for SMT>2), I don't
> think its worth doing outside of the core, and then we still need some
> powerpc (or any other architecture with abysmal atomics) tested.
FWIW Power has another 'fun' feature, their cores have asymmetric SMT.
Their cores have a static power level, based on _which_ SMT sibling is
running, not how many. A single SMT2 runs (much) slower than a single
SMT0.
So that random selection stuff really doesn't work well for them. Now
'sadly' x86 can also have ASYM_PACKING set on its SMT domain, so I'm
going to have to figure out what to do about all that.
next prev parent reply other threads:[~2018-02-05 17:04 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-29 23:31 [RESEND RFC PATCH V3] sched: Improve scalability of select_idle_sibling using SMT balance subhra mazumdar
2018-02-01 12:33 ` Peter Zijlstra
2018-02-01 13:33 ` Peter Zijlstra
2018-02-02 16:53 ` Steven Sistare
2018-02-02 17:17 ` Peter Zijlstra
2018-02-02 17:36 ` Steven Sistare
2018-02-02 19:58 ` Peter Zijlstra
2018-02-02 20:51 ` Steven Sistare
2018-02-02 17:37 ` Subhra Mazumdar
2018-02-05 12:19 ` Peter Zijlstra
2018-02-05 22:09 ` Subhra Mazumdar
2018-02-06 9:12 ` Peter Zijlstra
2018-02-07 0:30 ` Subhra Mazumdar
2018-02-07 8:42 ` Peter Zijlstra
2018-02-07 23:10 ` Subhra Mazumdar
2018-02-02 17:21 ` Peter Zijlstra
2018-02-02 17:39 ` Steven Sistare
2018-02-02 18:34 ` Steven Sistare
2018-02-02 20:04 ` Peter Zijlstra
2018-02-02 21:17 ` Steven Sistare
2018-02-03 3:47 ` Mike Galbraith
2018-02-02 19:59 ` Peter Zijlstra
2018-02-02 21:06 ` Steven Sistare
2018-02-05 12:48 ` Peter Zijlstra
2018-02-05 13:54 ` Mike Galbraith
2018-02-05 17:03 ` Peter Zijlstra [this message]
2018-02-05 22:32 ` Subhra Mazumdar
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