From: Dave Hansen <dave@sr71.net>
To: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Pekka Enberg <penberg@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/9] re-shrink 'struct page' when SLUB is on.
Date: Thu, 16 Jan 2014 09:08:36 -0800 [thread overview]
Message-ID: <52D81214.7070608@sr71.net> (raw)
In-Reply-To: <alpine.DEB.2.10.1401161041160.29778@nuc>
On 01/16/2014 08:44 AM, Christoph Lameter wrote:
> On Tue, 14 Jan 2014, Dave Hansen wrote:
>
>> On 01/14/2014 12:07 PM, Christoph Lameter wrote:
>>> One easy way to shrink struct page is to simply remove the feature. The
>>> patchset looked a bit complicated and does many other things.
>>
>> Sure. There's a clear path if you only care about 'struct page' size,
>> or if you only care about making the slub fast path as fast as possible.
>> We've got three variables, though:
>>
>> 1. slub fast path speed
>
> The fast path does use this_cpu_cmpxchg_double which is something
> different from a cmpxchg_double and its not used on struct page.
Yeah, I'm confusing the two. I might as well say: "slub speed when
touching 'struct page'"
>> Arranged in three basic choices:
>>
>> 1. Big 'struct page', fast, medium complexity code
>> 2. Small 'struct page', slow, lowest complexity
>
> The numbers that I see seem to indicate that a big struct page means slow.
This was a really tight loop where the caches are really hot, but it did
show the large 'struct page' winning:
http://sr71.net/~dave/intel/slub/slub-perf-20140109.png
As I said in the earlier description, the paravirt code doing interrupt
disabling was what really hurt the two spinlock cases.
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next prev parent reply other threads:[~2014-01-16 17:10 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-03 18:01 Dave Hansen
2014-01-03 18:01 ` [PATCH 1/9] mm: slab/slub: use page->list consistently instead of page->lru Dave Hansen
2014-01-03 18:01 ` [PATCH 2/9] mm: blk-mq: uses page->list incorrectly Dave Hansen
2014-01-03 18:01 ` [PATCH 3/9] mm: page->pfmemalloc only used by slab/skb Dave Hansen
2014-01-03 18:01 ` [PATCH 4/9] mm: slabs: reset page at free Dave Hansen
2014-01-03 18:01 ` [PATCH 5/9] mm: rearrange struct page Dave Hansen
2014-01-03 18:01 ` [PATCH 6/9] mm: slub: rearrange 'struct page' fields Dave Hansen
2014-01-03 18:02 ` [PATCH 7/9] mm: slub: abstract out double cmpxchg option Dave Hansen
2014-01-03 18:02 ` [PATCH 8/9] mm: slub: remove 'struct page' alignment restrictions Dave Hansen
2014-01-03 18:02 ` [PATCH 9/9] mm: slub: cleanups after code churn Dave Hansen
2014-01-03 22:18 ` [PATCH 0/9] re-shrink 'struct page' when SLUB is on Andrew Morton
2014-01-06 4:32 ` Joonsoo Kim
2014-01-10 20:52 ` Dave Hansen
2014-01-10 23:39 ` Andrew Morton
2014-01-10 23:42 ` Dave Hansen
2014-01-11 9:26 ` Pekka Enberg
2014-01-12 0:55 ` Christoph Lameter
2014-01-13 1:44 ` Joonsoo Kim
2014-01-13 3:36 ` Davidlohr Bueso
2014-01-13 13:46 ` Fengguang Wu
2014-01-13 15:42 ` Dave Hansen
2014-01-13 17:16 ` Dave Hansen
2014-01-14 20:07 ` Christoph Lameter
2014-01-14 22:05 ` Dave Hansen
2014-01-16 16:44 ` Christoph Lameter
2014-01-16 17:08 ` Dave Hansen [this message]
2014-01-16 18:26 ` Christoph Lameter
2014-01-14 17:40 ` Christoph Lameter
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