From: Peter Zijlstra <peterz@infradead.org>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Matt Fleming <matt@codeblueprint.co.uk>,
linux-kernel@vger.kernel.org, "Suthikulpanit,
Suravee" <Suravee.Suthikulpanit@amd.com>,
"Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH v3] sched/topology: Improve load balancing on AMD EPYC
Date: Tue, 23 Jul 2019 16:09:05 +0200 [thread overview]
Message-ID: <20190723140905.GF3402@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190723130321.GK24383@techsingularity.net>
On Tue, Jul 23, 2019 at 02:03:21PM +0100, Mel Gorman wrote:
> On Tue, Jul 23, 2019 at 02:00:30PM +0200, Peter Zijlstra wrote:
> > On Tue, Jul 23, 2019 at 12:42:48PM +0100, Mel Gorman wrote:
> > > On Tue, Jul 23, 2019 at 11:48:30AM +0100, Matt Fleming wrote:
> > > > Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
> > > > Cc: "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@amd.com>
> > > > Cc: Mel Gorman <mgorman@techsingularity.net>
> > > > Cc: "Lendacky, Thomas" <Thomas.Lendacky@amd.com>
> > > > Cc: Borislav Petkov <bp@alien8.de>
> > >
> > > Acked-by: Mel Gorman <mgorman@techsingularity.net>
> > >
> > > The only caveat I can think of is that a future generation of Zen might
> > > take a different magic number than 32 as their remote distance. If or
> > > when this happens, it'll need additional smarts but lacking a crystal
> > > ball, we can cross that bridge when we come to it.
> >
> > I just suggested to Matt on IRC we could do something along these lines,
> > but we can do that later.
> >
>
> That would seem fair but I do think it's something that could be done
> later (maybe 1 release away?) to avoid a false bisection to this patch by
> accident.
Quite agreed; changing reclaim_distance like that will affect a lot of
hardware, while the current patch limits the impact to just AMD-Zen
based bits.
> I don't *think* there are any machines out there with a 1-hop
> distance of 14 but if there is, your patch would make a difference to
> MM behaviour. In the same context, it might make sense to rename the
> value to somewhat reflective of the fact that "reclaim distance" affects
> scheduler placement. No good name springs to mind at the moment.
Yeah, naming sucks. Let us pain this bicycle shed blue!
next prev parent reply other threads:[~2019-07-23 14:09 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-23 10:48 [PATCH v3] sched/topology: Improve load balancing on AMD EPYC Matt Fleming
2019-07-23 11:42 ` Mel Gorman
2019-07-23 12:00 ` Peter Zijlstra
2019-07-23 13:03 ` Mel Gorman
2019-07-23 14:09 ` Peter Zijlstra [this message]
2019-07-25 16:37 ` Suthikulpanit, Suravee
2019-07-29 12:16 ` Matt Fleming
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