* [PATCH] sched: task_struct: Fill unconditional hole induced by sched_entity
@ 2021-09-24 2:54 Kees Cook
2021-10-06 4:48 ` Kees Cook
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Kees Cook @ 2021-09-24 2:54 UTC (permalink / raw)
To: Peter Zijlstra
Cc: Kees Cook, Ingo Molnar, Juri Lelli, Vincent Guittot,
Dietmar Eggemann, Steven Rostedt, Ben Segall, Mel Gorman,
Daniel Bristot de Oliveira, linux-kernel, linux-hardening
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>
---
include/linux/sched.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 39039ce8ac4c..27ed1d40028f 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;
--
2.30.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] sched: task_struct: Fill unconditional hole induced by sched_entity
2021-09-24 2:54 [PATCH] sched: task_struct: Fill unconditional hole induced by sched_entity Kees Cook
@ 2021-10-06 4:48 ` Kees Cook
2021-10-06 9:27 ` Peter Zijlstra
2021-10-09 10:07 ` [tip: sched/core] sched: " tip-bot2 for Kees Cook
2021-10-14 11:16 ` tip-bot2 for Kees Cook
2 siblings, 1 reply; 6+ messages in thread
From: Kees Cook @ 2021-10-06 4:48 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Thomas Gleixner, Borislav Petkov
Cc: x86, Juri Lelli, Vincent Guittot, Dietmar Eggemann,
Steven Rostedt, Ben Segall, Mel Gorman,
Daniel Bristot de Oliveira, linux-kernel, linux-hardening
On Thu, Sep 23, 2021 at 07:54:50PM -0700, Kees Cook wrote:
> 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:
Friendly ping. Can someone snag this for -tip please?
Thanks!
-Kees
>
> 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>
> ---
> include/linux/sched.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 39039ce8ac4c..27ed1d40028f 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;
> --
> 2.30.2
>
--
Kees Cook
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] sched: task_struct: Fill unconditional hole induced by sched_entity
2021-10-06 4:48 ` Kees Cook
@ 2021-10-06 9:27 ` Peter Zijlstra
2021-10-06 16:31 ` Kees Cook
0 siblings, 1 reply; 6+ messages in thread
From: Peter Zijlstra @ 2021-10-06 9:27 UTC (permalink / raw)
To: Kees Cook
Cc: Ingo Molnar, Thomas Gleixner, Borislav Petkov, x86, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Daniel Bristot de Oliveira, linux-kernel,
linux-hardening
On Tue, Oct 05, 2021 at 09:48:51PM -0700, Kees Cook wrote:
> On Thu, Sep 23, 2021 at 07:54:50PM -0700, Kees Cook wrote:
> > 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:
>
> Friendly ping. Can someone snag this for -tip please?
Hurpmf... if only we had like perf driven pahole output :/
Picked it up, we'll see what if anything hurts.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] sched: task_struct: Fill unconditional hole induced by sched_entity
2021-10-06 9:27 ` Peter Zijlstra
@ 2021-10-06 16:31 ` Kees Cook
0 siblings, 0 replies; 6+ messages in thread
From: Kees Cook @ 2021-10-06 16:31 UTC (permalink / raw)
To: Peter Zijlstra
Cc: Ingo Molnar, Thomas Gleixner, Borislav Petkov, x86, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Daniel Bristot de Oliveira, linux-kernel,
linux-hardening
On Wed, Oct 06, 2021 at 11:27:03AM +0200, Peter Zijlstra wrote:
> On Tue, Oct 05, 2021 at 09:48:51PM -0700, Kees Cook wrote:
> > On Thu, Sep 23, 2021 at 07:54:50PM -0700, Kees Cook wrote:
> > > 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:
> >
> > Friendly ping. Can someone snag this for -tip please?
>
> Hurpmf... if only we had like perf driven pahole output :/
Normally I wouldn't even make suggestions in task_struct given the high
variability due to CONFIG options, but this case was pretty universal.
> Picked it up, we'll see what if anything hurts.
Thanks! *fingers crossed*
--
Kees Cook
^ permalink raw reply [flat|nested] 6+ messages in thread
* [tip: sched/core] sched: Fill unconditional hole induced by sched_entity
2021-09-24 2:54 [PATCH] sched: task_struct: Fill unconditional hole induced by sched_entity Kees Cook
2021-10-06 4:48 ` Kees Cook
@ 2021-10-09 10:07 ` tip-bot2 for Kees Cook
2021-10-14 11:16 ` tip-bot2 for Kees Cook
2 siblings, 0 replies; 6+ messages in thread
From: tip-bot2 for Kees Cook @ 2021-10-09 10:07 UTC (permalink / raw)
To: linux-tip-commits; +Cc: Kees Cook, Peter Zijlstra (Intel), x86, linux-kernel
The following commit has been merged into the sched/core branch of tip:
Commit-ID: b2d5b9cec60fecc72a13191c2c6c05acf60975a5
Gitweb: https://git.kernel.org/tip/b2d5b9cec60fecc72a13191c2c6c05acf60975a5
Author: Kees Cook <keescook@chromium.org>
AuthorDate: Thu, 23 Sep 2021 19:54:50 -07:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Thu, 07 Oct 2021 13:51:17 +02:00
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
---
include/linux/sched.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 193e16e..343603f 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;
^ permalink raw reply related [flat|nested] 6+ messages in thread* [tip: sched/core] sched: Fill unconditional hole induced by sched_entity
2021-09-24 2:54 [PATCH] sched: task_struct: Fill unconditional hole induced by sched_entity Kees Cook
2021-10-06 4:48 ` Kees Cook
2021-10-09 10:07 ` [tip: sched/core] sched: " tip-bot2 for Kees Cook
@ 2021-10-14 11:16 ` tip-bot2 for Kees Cook
2 siblings, 0 replies; 6+ messages in thread
From: tip-bot2 for Kees Cook @ 2021-10-14 11:16 UTC (permalink / raw)
To: linux-tip-commits; +Cc: Kees Cook, Peter Zijlstra (Intel), x86, linux-kernel
The following commit has been merged into the sched/core branch of tip:
Commit-ID: 804bccba71a57e7e5deb507a4c8ebbab730909c0
Gitweb: https://git.kernel.org/tip/804bccba71a57e7e5deb507a4c8ebbab730909c0
Author: Kees Cook <keescook@chromium.org>
AuthorDate: Thu, 23 Sep 2021 19:54:50 -07:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Thu, 14 Oct 2021 13:09:58 +02:00
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
---
include/linux/sched.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 193e16e..343603f 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;
^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-10-14 11:16 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-24 2:54 [PATCH] sched: task_struct: Fill unconditional hole induced by sched_entity Kees Cook
2021-10-06 4:48 ` Kees Cook
2021-10-06 9:27 ` Peter Zijlstra
2021-10-06 16:31 ` Kees Cook
2021-10-09 10:07 ` [tip: sched/core] sched: " tip-bot2 for Kees Cook
2021-10-14 11:16 ` tip-bot2 for Kees Cook
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.