From 33166b1ffca5e1945246bcaa77d72a22b0d3e531 Mon Sep 17 00:00:00 2001 From: Richard Kennedy Date: Fri, 25 Jul 2008 01:48:35 -0700 Subject: [PATCH] shrink struct pid by removing padding on 64 bit builds When struct pid is built on a 64 bit platform gcc has to insert padding to maintain the correct alignment, by simply reordering its members the memory usage shrinks from 88 bytes to 80. I've successfully run with this patch on my desktop AMD64 machine. There are no significant kernel size changes to a default config.X86_64 on the latest git v2.6.26-rc1 text data bss dec hex filename 5404828 976760 734280 7115868 6c945c vmlinux 5404811 976760 734280 7115851 6c944b vmlinux.pid-patch Acked-by: "Eric W. Biederman" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/pid.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/pid.h b/include/linux/pid.h index c21c7e8..6f084b9 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -57,10 +57,10 @@ struct upid { struct pid { atomic_t count; + unsigned int level; /* lists of tasks that use this pid */ struct hlist_head tasks[PIDTYPE_MAX]; struct rcu_head rcu; - unsigned int level; struct upid numbers[1]; }; -- 2.7.4