From: Christoph Lameter <cl@linux.com>
To: Glauber Costa <glommer@parallels.com>
Cc: Pekka Enberg <penberg@kernel.org>, Joonsoo Kim <js1304@gmail.com>,
linux-mm@kvack.org, David Rientjes <rientjes@google.com>,
elezegarcia@gmail.com
Subject: Re: CK2 [07/15] Common kmalloc slab index determination
Date: Tue, 23 Oct 2012 20:48:32 +0000 [thread overview]
Message-ID: <0000013a8f624485-3e5c3678-4534-4d2c-9546-97d62bbfd6f9-000000@email.amazonses.com> (raw)
In-Reply-To: <508515B4.1090303@parallels.com>
On Mon, 22 Oct 2012, Glauber Costa wrote:
> It is still unclear to me if the above is really better than
> ilog2(size -1) + 1
Hmmm... We could change that if ilog2 is now supported on all platforms
and works right. That was not the case a couple of years ago (I believe
2008) when I tried to use ilog.
> For that case, gcc seems to generate dec + brs + inc which at some point
> will be faster than walking a jump table. At least for dynamically-sized
> allocations. The code size is definitely smaller, and this is always
> inline... Anyway, this is totally separate.
Indeed I would favor that approach but it did not work out for all
platforms the last time around. Compiler was getting into issues to do the
constant folding too.
> The patch also seem to have some churn for the slob for no reason: you
> have a patch just to move the kmalloc definitions, would maybe be better
> to do it in there to decrease the # of changes in this one, which is
> more complicated.
Ok. Will look at that.
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next prev parent reply other threads:[~2012-10-23 20:48 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20121019142254.724806786@linux.com>
2012-10-19 14:25 ` CK2 [02/15] create common functions for boot slab creation Christoph Lameter
2012-10-20 15:57 ` JoonSoo Kim
2012-10-19 14:25 ` CK2 [01/15] slab: Simplify bootstrap Christoph Lameter
2012-10-22 7:57 ` Glauber Costa
2012-10-23 20:45 ` Christoph Lameter
2012-10-19 14:32 ` CK2 [14/15] stat: Use size_t for sizes instead of unsigned Christoph Lameter
2012-10-22 8:42 ` Glauber Costa
2012-10-19 14:32 ` CK2 [12/15] Common definition for the array of kmalloc caches Christoph Lameter
2012-10-19 14:32 ` CK2 [05/15] Common alignment code Christoph Lameter
2012-10-19 14:42 ` CK2 [04/15] slab: Use the new create_boot_cache function to simplify bootstrap Christoph Lameter
2012-10-20 16:01 ` JoonSoo Kim
2012-10-22 8:09 ` Glauber Costa
2012-10-23 21:40 ` Christoph Lameter
2012-10-19 14:42 ` CK2 [13/15] Common function to create the kmalloc array Christoph Lameter
2012-10-22 9:51 ` Glauber Costa
2012-10-19 14:42 ` CK2 [15/15] Common Kmalloc cache determination Christoph Lameter
2012-10-20 16:20 ` JoonSoo Kim
2012-10-23 20:40 ` Christoph Lameter
2012-10-19 14:45 ` CK2 [08/15] slab: Use common kmalloc_index/kmalloc_size functions Christoph Lameter
2012-10-20 16:12 ` JoonSoo Kim
2012-10-23 20:39 ` Christoph Lameter
2012-10-24 17:47 ` JoonSoo Kim
2012-10-19 14:49 ` CK2 [09/15] slab: Common name for the per node structures Christoph Lameter
2012-10-20 16:14 ` JoonSoo Kim
2012-10-23 20:39 ` Christoph Lameter
2012-10-22 8:32 ` Glauber Costa
2012-10-19 14:51 ` CK2 [03/15] slub: Use a statically allocated kmem_cache boot structure for bootstrap Christoph Lameter
2012-10-19 14:51 ` CK2 [06/15] Move kmalloc related function defs Christoph Lameter
2012-10-22 8:11 ` Glauber Costa
2012-10-19 14:51 ` CK2 [07/15] Common kmalloc slab index determination Christoph Lameter
2012-10-22 9:45 ` Glauber Costa
2012-10-23 20:48 ` Christoph Lameter [this message]
2012-10-19 14:51 ` CK2 [10/15] slab: rename nodelists to node Christoph Lameter
2012-10-22 8:34 ` Glauber Costa
2012-10-19 14:58 ` CK2 [11/15] Common constants for kmalloc boundaries Christoph Lameter
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