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From: Mike Rapoport <rppt@kernel.org>
To: Bruno Faccini <bfaccini@nvidia.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	Zi Yan <ziy@nvidia.com>, Timur Tabi <ttabi@nvidia.com>,
	John Hubbard <jhubbard@nvidia.com>
Subject: Re: [PATCH] mm/fake-numa: per-phys node fake size
Date: Tue, 1 Oct 2024 10:15:38 +0300	[thread overview]
Message-ID: <Zvuhmv7exzL8sMoW@kernel.org> (raw)
In-Reply-To: <9759DD75-5DA6-4C3A-8300-CD8EA8353BAF@nvidia.com>

On Sun, Sep 29, 2024 at 03:43:50PM +0000, Bruno Faccini wrote:
> 
> On 25/09/2024 11:32, "Mike Rapoport" <rppt@kernel.org <mailto:rppt@kernel.org>> wrote:
> > On Tue, Sep 24, 2024 at 03:27:52PM +0000, Bruno Faccini wrote:
> > > On 24/09/2024 12:43, "Mike Rapoport" <rppt@kernel.org <mailto:rppt@kernel.org>> wrote:
> >
> > > I don't think that fake=N allocation method is intended to get fake nodes
> > > with equal size, but to get this exact number of nodes. This is why I
> > > think we should use a per-phys node size for the fake nodes it will host.
> >
> > IMO your change adds to much complexity for a feature that by definition
> > should be used only for debugging.
> 
> Well it is only executed once during boot, and as you said for debugging,
> so I believe when the boot speed is not a requirement.  And my testing on
> our fat Numa nodes did not show a real difference.

I meant code complexity, not the execution complexity.
 
> > Also, there is a variation numa=fake=<N>U of numa=fake parameter that
> > divides each node into N emulated nodes.
> 
> Right, but both methods should work as expected, is'nt it ?
> And one allocates emulated nodes interleaved on physical nodes when the
> second is doing allocation serially.

I think we can just bail out with an error if we fail to create the
requested emulated nodes.

-- 
Sincerely yours,
Mike.


      reply	other threads:[~2024-10-01  7:19 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-09-21  8:13 [PATCH] mm/fake-numa: per-phys node fake size Bruno Faccini
2024-09-24 10:40 ` Mike Rapoport
2024-09-24 15:27   ` Bruno Faccini
2024-09-25  9:28     ` Mike Rapoport
2024-09-29 15:43       ` Bruno Faccini
2024-10-01  7:15         ` Mike Rapoport [this message]

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