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authorWilliam Cohen <wcohen@redhat.com>2007-05-08 00:23:41 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-08 11:14:58 -0700
commit97dc32cdb1b53832801159d5f634b41aad9d0a23 (patch)
tree438f59c84d3528de5f68583d312beceb1aa32659 /fs/proc
parent4d7bf11d649c72621ca31b8ea12b9c94af380e63 (diff)
downloadop-kernel-dev-97dc32cdb1b53832801159d5f634b41aad9d0a23.zip
op-kernel-dev-97dc32cdb1b53832801159d5f634b41aad9d0a23.tar.gz
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: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
-rw-r--r--fs/proc/array.c4
1 files changed, 2 insertions, 2 deletions
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,
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