[PATCH] RCU : move three variables to __read_mostly to save space

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From: Eric Dumazet <dada1@...>

To: Andrew Morton <akpm@...>

Cc: Dipankar Sarma <dipankar@...>, Linux kernel <linux-kernel@...>

Subject: [PATCH] RCU : move three variables to __read_mostly to save space

Date: Tuesday, December 11, 2007 - 12:50 am

I noticed this vmlinux layout on i686 (where CONFIG_X86_L1_CACHE_SHIFT = 7) :

c06cdab4 d pid_caches_lh
c06cdb00 d qlowmark
c06cdb04 d qhimark
c06cdb08 d blimit
c06cdb80 d rcu_ctrlblk
c06cdc80 d rcu_bh_ctrlblk

This means that qlowmark, qhimark and blimit use a whole 128 bytes cache line.
Linker is not smart enough for us.

Moving these three variables to read_mostly section saves 116 (128-12) bytes.

# size vmlinux vmlinux.before_patch
text data bss dec hex filename
6343966 490818 630784 7465568 71ea60 vmlinux
6343966 490930 630784 7465680 71ead0 vmlinux.before_patch

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>


linux-kernel:
Greg Kroah-Hartman	[PATCH 001/196] Chinese: Add the known_regression URI to the HOWTO
Andrew Morton	-mm merge plans for 2.6.23
david	Re: Dual-Licensing Linux Kernel with GPL V2 and GPL V3
Bart Van Assche	Integration of SCST in the mainstream Linux kernel
git:

linux-netdev:
Gerrit Renker	[PATCH 27/37] dccp: Integration of dynamic feature activation - part 2 (server side)
David Miller	Re: [PATCH] pkt_sched: Destroy gen estimators under rtnl_lock().
PJ Waskiewicz	[ANNOUNCE] ixgbe: Data Center Bridging (DCB) support for ixgbe
David Miller	Re: [GIT]: Networking
openbsd-misc:

[PATCH] RCU : move three variables to __read_mostly to save space

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