From: Peter Zijlstra <peterz@infradead.org>
To: Rohit Jain <rohit.k.jain@oracle.com>
Cc: linux-kernel@vger.kernel.org, mingo@redhat.com,
steven.sistare@oracle.com, joelaf@google.com, jbacik@fb.com,
riel@redhat.com, juri.lelli@redhat.com, dhaval.giani@oracle.com,
efault@gmx.de
Subject: Re: [RFC 2/2] Introduce sysctl(s) for the migration costs
Date: Mon, 12 Feb 2018 16:28:55 +0100 [thread overview]
Message-ID: <20180212152855.GV25201@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1518128395-14606-3-git-send-email-rohit.k.jain@oracle.com>
On Thu, Feb 08, 2018 at 02:19:55PM -0800, Rohit Jain wrote:
> This patch introduces the sysctl for sched_domain based migration costs.
> These in turn can be used for performance tuning of workloads.
Smells like a bad attempt to (again) revive commit:
0437e109e184 ("sched: zap the migration init / cache-hot balancing code")
Yes, the migration cost would ideally be per domain, in practise it all
sucks because more tunables is more confusion. And as that commit
states, runtime measurements suck too, they cause run-to-run variation
which causes repeatability issues and degrade boot times.
Static numbers suck worse, because they'll be wrong for everyone.
prev parent reply other threads:[~2018-02-12 15:29 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-08 22:19 [RFC 0/2] sched: Make idle_balance smarter about topology Rohit Jain
2018-02-08 22:19 ` [RFC 1/2] sched: reduce migration cost between faster caches for idle_balance Rohit Jain
2018-02-09 3:42 ` Mike Galbraith
2018-02-09 16:08 ` Steven Sistare
2018-02-10 6:37 ` Mike Galbraith
2018-02-15 16:35 ` Steven Sistare
2018-02-15 18:07 ` Mike Galbraith
2018-02-15 18:21 ` Steven Sistare
2018-02-15 18:39 ` Mike Galbraith
2018-02-15 18:07 ` Rohit Jain
2018-02-16 4:53 ` Mike Galbraith
2018-02-08 22:19 ` [RFC 2/2] Introduce sysctl(s) for the migration costs Rohit Jain
2018-02-09 3:54 ` Mike Galbraith
2018-02-09 16:10 ` Steven Sistare
2018-02-09 17:08 ` Mike Galbraith
2018-02-09 17:33 ` Steven Sistare
2018-02-09 17:50 ` Mike Galbraith
2018-02-12 15:28 ` Peter Zijlstra [this message]
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