[PATCH] scheduler: reorder task_struct to reduce padding on 64bitbuilds

From: Richard Kennedy
Date: Thu May 15 2008 - 07:19:44 EST


reorder task_struct to reduce padding on 64bit builds

removes 24 bytes on my config and /proc/slabinfo reports +1 objects per slab

Signed-off-by: Richard Kennedy <richard@xxxxxxxxxxxxxxx>

---
This patch removes 24 bytes of padding and allows 1 extra object per
slab on my fedora based config.
Patch against 2.6.26-rc2 & running successfully on my AMD 64 desktop
machine.

Richard



diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5395a61..386e154 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1040,6 +1040,7 @@ struct task_struct {
#endif

int prio, static_prio, normal_prio;
+ unsigned int rt_priority;
const struct sched_class *sched_class;
struct sched_entity se;
struct sched_rt_entity rt;
@@ -1123,7 +1124,6 @@ struct task_struct {
int __user *set_child_tid; /* CLONE_CHILD_SETTID */
int __user *clear_child_tid; /* CLONE_CHILD_CLEARTID */

- unsigned int rt_priority;
cputime_t utime, stime, utimescaled, stimescaled;
cputime_t gtime;
cputime_t prev_utime, prev_stime;
@@ -1142,12 +1142,12 @@ struct task_struct {
gid_t gid,egid,sgid,fsgid;
struct group_info *group_info;
kernel_cap_t cap_effective, cap_inheritable, cap_permitted, cap_bset;
- unsigned securebits;
struct user_struct *user;
+ unsigned securebits;
#ifdef CONFIG_KEYS
+ unsigned char jit_keyring; /* default keyring to attach requested keys to */
struct key *request_key_auth; /* assumed request_key authority */
struct key *thread_keyring; /* keyring private to this thread */
- unsigned char jit_keyring; /* default keyring to attach requested keys to */
#endif
char comm[TASK_COMM_LEN]; /* executable name excluding path
- access with [gs]et_task_comm (which lock
@@ -1234,8 +1234,8 @@ struct task_struct {
# define MAX_LOCK_DEPTH 48UL
u64 curr_chain_key;
int lockdep_depth;
- struct held_lock held_locks[MAX_LOCK_DEPTH];
unsigned int lockdep_recursion;
+ struct held_lock held_locks[MAX_LOCK_DEPTH];
#endif

/* journalling filesystem info */
@@ -1263,10 +1263,6 @@ struct task_struct {
u64 acct_vm_mem1; /* accumulated virtual memory usage */
cputime_t acct_stimexpd;/* stime since last update */
#endif
-#ifdef CONFIG_NUMA
- struct mempolicy *mempolicy;
- short il_next;
-#endif
#ifdef CONFIG_CPUSETS
nodemask_t mems_allowed;
int cpuset_mems_generation;
@@ -1286,6 +1282,10 @@ struct task_struct {
struct list_head pi_state_list;
struct futex_pi_state *pi_state_cache;
#endif
+#ifdef CONFIG_NUMA
+ struct mempolicy *mempolicy;
+ short il_next;
+#endif
atomic_t fs_excl; /* holding fs exclusive resources */
struct rcu_head rcu;



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