The patch titled
Subject: epoll: trim epitem by one cache line
has been added to the -mm tree. Its filename is
epoll-trim-epitem-by-one-cache-line-on-x86_64.patch
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The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Eric Wong <normalperson@xxxxxxxx>
Subject: epoll: trim epitem by one cache line
It is common for epoll users to have thousands of epitems, so saving a
cache line on every allocation leads to large memory savings.
Since epitem allocations are cache-aligned, reducing sizeof(struct epitem)
from 136 bytes to 128 bytes will allow it to squeeze under a cache line
boundary on x86_64.
Via /sys/kernel/slab/eventpoll_epi, I see the following changes on my
x86_64 Core2 Duo (which has 64-byte cache alignment):
object_size : 192 => 128
objs_per_slab: 21 => 32
Signed-off-by: Eric Wong <normalperson@xxxxxxxx>
Cc: Davide Libenzi <davidel@xxxxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/eventpoll.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN fs/eventpoll.c~epoll-trim-epitem-by-one-cache-line-on-x86_64 fs/eventpoll.c
--- a/fs/eventpoll.c~epoll-trim-epitem-by-one-cache-line-on-x86_64
+++ a/fs/eventpoll.c
@@ -105,7 +105,7 @@
struct epoll_filefd {
struct file *file;
int fd;
-};
+} EPOLL_PACKED;
/*
* Structure used to track possible nested calls, for too deep recursions
_
Patches currently in -mm which might be from normalperson@xxxxxxxx are
epoll-trim-epitem-by-one-cache-line-on-x86_64.patch
epoll-trim-epitem-by-one-cache-line-on-x86_64-fix.patch
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