From 97dc32cdb1b53832801159d5f634b41aad9d0a23 Mon Sep 17 00:00:00 2001 From: William Cohen Date: Tue, 8 May 2007 00:23:41 -0700 Subject: reduce size of task_struct on 64-bit machines This past week I was playing around with that pahole tool (http://oops.ghostprotocols.net:81/acme/dwarves/) and looking at the size of various struct in the kernel. I was surprised by the size of the task_struct on x86_64, approaching 4K. I looked through the fields in task_struct and found that a number of them were declared as "unsigned long" rather than "unsigned int" despite them appearing okay as 32-bit sized fields. On x86_64 "unsigned long" ends up being 8 bytes in size and forces 8 byte alignment. Is there a reason there a reason they are "unsigned long"? The patch below drops the size of the struct from 3808 bytes (60 64-byte cachelines) to 3760 bytes (59 64-byte cachelines). A couple other fields in the task struct take a signficant amount of space: struct thread_struct thread; 688 struct held_lock held_locks[30]; 1680 CONFIG_LOCKDEP is turned on in the .config [akpm@linux-foundation.org: fix printk warnings] Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/array.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'fs/proc') diff --git a/fs/proc/array.c b/fs/proc/array.c index 07c9cdb..74f30e0 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -410,9 +410,9 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole) /* convert nsec -> ticks */ start_time = nsec_to_clock_t(start_time); - res = sprintf(buffer,"%d (%s) %c %d %d %d %d %d %lu %lu \ + res = sprintf(buffer,"%d (%s) %c %d %d %d %d %d %u %lu \ %lu %lu %lu %lu %lu %ld %ld %ld %ld %d 0 %llu %lu %ld %lu %lu %lu %lu %lu \ -%lu %lu %lu %lu %lu %lu %lu %lu %d %d %lu %lu %llu\n", +%lu %lu %lu %lu %lu %lu %lu %lu %d %d %u %u %llu\n", task->pid, tcomm, state, -- cgit v1.1