* [PATCH] io: remove padding from io_context on 64bit builds
@ 2010-02-26 12:56 Richard Kennedy
2010-02-26 13:01 ` Jens Axboe
0 siblings, 1 reply; 2+ messages in thread
From: Richard Kennedy @ 2010-02-26 12:56 UTC (permalink / raw)
To: Jens Axboe, Andrew Morton, Nikanth Karthikesan, Jeff Moyer,
Vivek Goyal
Cc: lkml
On 64 bit builds when CONFIG_BLK_CGROUP=n (the default) this removes 8
bytes of padding from structure io_context and drops its size from 72 to
64 bytes, so needing one fewer cachelines and allowing more objects per
slab in it's kmem_cache.
Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
----
patch against 2.6.33
compiled & test on x86_64 AMDX2
regards
Richard
diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h
index 78ef023..1195a80 100644
--- a/include/linux/iocontext.h
+++ b/include/linux/iocontext.h
@@ -49,8 +49,8 @@ struct io_context {
/*
* For request batching
*/
- unsigned long last_waited; /* Time last woken after wait for request */
int nr_batch_requests; /* Number of requests left in the batch */
+ unsigned long last_waited; /* Time last woken after wait for request */
struct radix_tree_root radix_root;
struct hlist_head cic_list;
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] io: remove padding from io_context on 64bit builds
2010-02-26 12:56 [PATCH] io: remove padding from io_context on 64bit builds Richard Kennedy
@ 2010-02-26 13:01 ` Jens Axboe
0 siblings, 0 replies; 2+ messages in thread
From: Jens Axboe @ 2010-02-26 13:01 UTC (permalink / raw)
To: Richard Kennedy
Cc: Andrew Morton, Nikanth Karthikesan, Jeff Moyer, Vivek Goyal, lkml
On Fri, Feb 26 2010, Richard Kennedy wrote:
> On 64 bit builds when CONFIG_BLK_CGROUP=n (the default) this removes 8
> bytes of padding from structure io_context and drops its size from 72 to
> 64 bytes, so needing one fewer cachelines and allowing more objects per
> slab in it's kmem_cache.
>
> Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Thanks Richard, applied.
--
Jens Axboe
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2010-02-26 12:56 [PATCH] io: remove padding from io_context on 64bit builds Richard Kennedy
2010-02-26 13:01 ` Jens Axboe
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