From: Josh Triplett <josh@joshtriplett.org>
To: Alexander Duyck <alexander.duyck@gmail.com>,
Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Herbert Xu <herbert@gondor.apana.org.au>,
Steffen Klassert <steffen.klassert@secunet.com>,
Alex Williamson <alex.williamson@redhat.com>,
Alexander Duyck <alexander.h.duyck@linux.intel.com>,
Dan Williams <dan.j.williams@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
David Hildenbrand <david@redhat.com>,
Jason Gunthorpe <jgg@ziepe.ca>, Jonathan Corbet <corbet@lwn.net>,
Kirill Tkhai <ktkhai@virtuozzo.com>,
Michal Hocko <mhocko@kernel.org>, Pavel Machek <pavel@ucw.cz>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
Peter Zijlstra <peterz@infradead.org>,
Randy Dunlap <rdunlap@infradead.org>,
Shile Zhang <shile.zhang@linux.alibaba.com>,
Tejun Heo <tj@kernel.org>, Zi Yan <ziy@nvidia.com>,
linux-crypto@vger.kernel.org, linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 6/7] mm: parallelize deferred_init_memmap()
Date: Mon, 04 May 2020 16:38:03 -0700 [thread overview]
Message-ID: <3C3C62BE-6363-41C3-834C-C3124EB3FFAB@joshtriplett.org> (raw)
In-Reply-To: <CAKgT0Uf7e5514SOi8dmkB5oXUK9bwqD_z-5KJ_F3MUn3CAQyPQ@mail.gmail.com>
On May 4, 2020 3:33:58 PM PDT, Alexander Duyck <alexander.duyck@gmail.com> wrote:
>On Thu, Apr 30, 2020 at 1:12 PM Daniel Jordan
><daniel.m.jordan@oracle.com> wrote:
>> /*
>> - * Initialize and free pages in MAX_ORDER sized increments so
>> - * that we can avoid introducing any issues with the buddy
>> - * allocator.
>> + * More CPUs always led to greater speedups on tested
>systems, up to
>> + * all the nodes' CPUs. Use all since the system is
>otherwise idle now.
>> */
>
>I would be curious about your data. That isn't what I have seen in the
>past. Typically only up to about 8 or 10 CPUs gives you any benefit,
>beyond that I was usually cache/memory bandwidth bound.
I've found pretty much linear performance up to memory bandwidth, and on the systems I was testing, I didn't saturate memory bandwidth until about the full number of physical cores. From number of cores up to number of threads, the performance stayed about flat; it didn't get any better or worse.
- Josh
WARNING: multiple messages have this Message-ID (diff)
From: Josh Triplett <josh@joshtriplett.org>
To: Alexander Duyck <alexander.duyck@gmail.com>,Daniel Jordan
<daniel.m.jordan@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,Herbert Xu
<herbert@gondor.apana.org.au>,Steffen Klassert
<steffen.klassert@secunet.com>,Alex Williamson
<alex.williamson@redhat.com>,Alexander Duyck
<alexander.h.duyck@linux.intel.com>,Dan Williams
<dan.j.williams@intel.com>,Dave Hansen
<dave.hansen@linux.intel.com>,David Hildenbrand
<david@redhat.com>,Jason Gunthorpe <jgg@ziepe.ca>,Jonathan
Corbet <corbet@lwn.net>,Kirill Tkhai
<ktkhai@virtuozzo.com>,Michal Hocko <mhocko@kernel.org>,Pavel
Machek <pavel@ucw.cz>,Pavel Tatashin
<pasha.tatashin@soleen.com>,Peter Zijlstra
<peterz@infradead.org>,Randy Dunlap
<rdunlap@infradead.org>,Shile Zhang
<shile.zhang@linux.alibaba.com>,Tejun Heo <tj@kernel.org>,Zi Yan
<ziy@nvidia.com>,linux-crypto@vger.kernel.org,linux-mm
<linux-mm@kvack.org>,LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 6/7] mm: parallelize deferred_init_memmap()
Date: Mon, 04 May 2020 16:38:03 -0700 [thread overview]
Message-ID: <3C3C62BE-6363-41C3-834C-C3124EB3FFAB@joshtriplett.org> (raw)
In-Reply-To: <CAKgT0Uf7e5514SOi8dmkB5oXUK9bwqD_z-5KJ_F3MUn3CAQyPQ@mail.gmail.com>
On May 4, 2020 3:33:58 PM PDT, Alexander Duyck <alexander.duyck@gmail.com> wrote:
>On Thu, Apr 30, 2020 at 1:12 PM Daniel Jordan
><daniel.m.jordan@oracle.com> wrote:
>> /*
>> - * Initialize and free pages in MAX_ORDER sized increments so
>> - * that we can avoid introducing any issues with the buddy
>> - * allocator.
>> + * More CPUs always led to greater speedups on tested
>systems, up to
>> + * all the nodes' CPUs. Use all since the system is
>otherwise idle now.
>> */
>
>I would be curious about your data. That isn't what I have seen in the
>past. Typically only up to about 8 or 10 CPUs gives you any benefit,
>beyond that I was usually cache/memory bandwidth bound.
I've found pretty much linear performance up to memory bandwidth, and on the systems I was testing, I didn't saturate memory bandwidth until about the full number of physical cores. From number of cores up to number of threads, the performance stayed about flat; it didn't get any better or worse.
- Josh
next prev parent reply other threads:[~2020-05-04 23:44 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-30 20:11 [PATCH 0/7] padata: parallelize deferred page init Daniel Jordan
2020-04-30 20:11 ` [PATCH 1/7] padata: remove exit routine Daniel Jordan
2020-04-30 20:11 ` [PATCH 2/7] padata: initialize earlier Daniel Jordan
2020-04-30 20:11 ` [PATCH 3/7] padata: allocate work structures for parallel jobs from a pool Daniel Jordan
2020-04-30 20:11 ` [PATCH 4/7] padata: add basic support for multithreaded jobs Daniel Jordan
2020-04-30 20:11 ` [PATCH 5/7] mm: move zone iterator outside of deferred_init_maxorder() Daniel Jordan
2020-04-30 21:43 ` Alexander Duyck
2020-05-01 2:45 ` Daniel Jordan
2020-05-04 22:10 ` Alexander Duyck
2020-05-04 22:10 ` Alexander Duyck
2020-05-05 0:54 ` Daniel Jordan
2020-05-05 15:27 ` Alexander Duyck
2020-05-05 15:27 ` Alexander Duyck
2020-05-06 22:39 ` Daniel Jordan
2020-05-07 15:26 ` Alexander Duyck
2020-05-07 15:26 ` Alexander Duyck
2020-05-07 20:20 ` Daniel Jordan
2020-05-07 21:18 ` Alexander Duyck
2020-05-07 21:18 ` Alexander Duyck
2020-05-07 22:15 ` Daniel Jordan
2020-04-30 20:11 ` [PATCH 6/7] mm: parallelize deferred_init_memmap() Daniel Jordan
2020-05-04 22:33 ` Alexander Duyck
2020-05-04 22:33 ` Alexander Duyck
2020-05-04 23:38 ` Josh Triplett [this message]
2020-05-04 23:38 ` Josh Triplett
2020-05-05 0:40 ` Alexander Duyck
2020-05-05 0:40 ` Alexander Duyck
2020-05-05 1:48 ` Daniel Jordan
2020-05-05 2:09 ` Daniel Jordan
2020-05-05 14:55 ` Alexander Duyck
2020-05-05 14:55 ` Alexander Duyck
2020-05-06 22:21 ` Daniel Jordan
2020-05-06 22:36 ` Alexander Duyck
2020-05-06 22:36 ` Alexander Duyck
2020-05-06 22:43 ` Daniel Jordan
2020-05-06 23:01 ` Daniel Jordan
2020-05-05 1:26 ` Daniel Jordan
2020-04-30 20:11 ` [PATCH 7/7] padata: document multithreaded jobs Daniel Jordan
2020-04-30 21:31 ` [PATCH 0/7] padata: parallelize deferred page init Andrew Morton
2020-04-30 21:40 ` Pavel Tatashin
2020-04-30 21:40 ` Pavel Tatashin
2020-05-01 2:40 ` Daniel Jordan
2020-05-01 0:50 ` Josh Triplett
2020-05-01 1:09 ` Josh Triplett
2020-05-01 2:48 ` Daniel Jordan
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