diff options
| author | William Cohen <wcohen@redhat.com> | 2007-05-08 11:23:41 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-08 22:14:58 +0400 |
| commit | 97dc32cdb1b53832801159d5f634b41aad9d0a23 (patch) | |
| tree | 438f59c84d3528de5f68583d312beceb1aa32659 /include | |
| parent | 4d7bf11d649c72621ca31b8ea12b9c94af380e63 (diff) | |
| download | linux-97dc32cdb1b53832801159d5f634b41aad9d0a23.tar.xz | |
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 'include')
| -rw-r--r-- | include/linux/sched.h | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index a1707583de49..d9acbbb39f96 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -801,8 +801,8 @@ struct task_struct { volatile long state; /* -1 unrunnable, 0 runnable, >0 stopped */ struct thread_info *thread_info; atomic_t usage; - unsigned long flags; /* per process flags, defined below */ - unsigned long ptrace; + unsigned int flags; /* per process flags, defined below */ + unsigned int ptrace; int lock_depth; /* BKL lock depth */ @@ -825,7 +825,7 @@ struct task_struct { unsigned long long sched_time; /* sched_clock time spent running */ enum sleep_type sleep_type; - unsigned long policy; + unsigned int policy; cpumask_t cpus_allowed; unsigned int time_slice, first_time_slice; @@ -845,11 +845,11 @@ struct task_struct { /* task state */ struct linux_binfmt *binfmt; - long exit_state; + int exit_state; int exit_code, exit_signal; int pdeath_signal; /* The signal sent when the parent dies */ /* ??? */ - unsigned long personality; + unsigned int personality; unsigned did_exec:1; pid_t pid; pid_t tgid; @@ -881,7 +881,7 @@ struct task_struct { int __user *set_child_tid; /* CLONE_CHILD_SETTID */ int __user *clear_child_tid; /* CLONE_CHILD_CLEARTID */ - unsigned long rt_priority; + unsigned int rt_priority; cputime_t utime, stime; unsigned long nvcsw, nivcsw; /* context switch counts */ struct timespec start_time; |