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| author | Kees Cook <keescook@chromium.org> | 2021-09-23 19:54:50 -0700 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-10-14 13:09:58 +0200 |
| commit | 804bccba71a57e7e5deb507a4c8ebbab730909c0 (patch) | |
| tree | 207a9690754ebb3935241949e4f75a973c033e5f /include/linux/sched.h | |
| parent | 4ef0c5c6b5ba1f38f0ea1cedad0cad722f00c14a (diff) | |
| download | lwn-804bccba71a57e7e5deb507a4c8ebbab730909c0.tar.gz lwn-804bccba71a57e7e5deb507a4c8ebbab730909c0.zip | |
sched: Fill unconditional hole induced by sched_entity
With struct sched_entity before the other sched entities, its alignment
won't induce a struct hole. This saves 64 bytes in defconfig task_struct:
Before:
...
unsigned int rt_priority; /* 120 4 */
/* XXX 4 bytes hole, try to pack */
/* --- cacheline 2 boundary (128 bytes) --- */
const struct sched_class * sched_class; /* 128 8 */
/* XXX 56 bytes hole, try to pack */
/* --- cacheline 3 boundary (192 bytes) --- */
struct sched_entity se __attribute__((__aligned__(64))); /* 192 448 */
/* --- cacheline 10 boundary (640 bytes) --- */
struct sched_rt_entity rt; /* 640 48 */
struct sched_dl_entity dl __attribute__((__aligned__(8))); /* 688 224 */
/* --- cacheline 14 boundary (896 bytes) was 16 bytes ago --- */
After:
...
unsigned int rt_priority; /* 120 4 */
/* XXX 4 bytes hole, try to pack */
/* --- cacheline 2 boundary (128 bytes) --- */
struct sched_entity se __attribute__((__aligned__(64))); /* 128 448 */
/* --- cacheline 9 boundary (576 bytes) --- */
struct sched_rt_entity rt; /* 576 48 */
struct sched_dl_entity dl __attribute__((__aligned__(8))); /* 624 224 */
/* --- cacheline 13 boundary (832 bytes) was 16 bytes ago --- */
Summary diff:
- /* size: 7040, cachelines: 110, members: 188 */
+ /* size: 6976, cachelines: 109, members: 188 */
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210924025450.4138503-1-keescook@chromium.org
Diffstat (limited to 'include/linux/sched.h')
| -rw-r--r-- | include/linux/sched.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 193e16e2d0e4..343603f77f8b 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -775,10 +775,10 @@ struct task_struct { int normal_prio; unsigned int rt_priority; - const struct sched_class *sched_class; struct sched_entity se; struct sched_rt_entity rt; struct sched_dl_entity dl; + const struct sched_class *sched_class; #ifdef CONFIG_SCHED_CORE struct rb_node core_node; |