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| author | Peter Zijlstra <peterz@infradead.org> | 2018-04-05 10:05:21 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-04-05 10:56:16 +0200 |
| commit | 317d359df95dd0cb7653d09b7fc513770590cf85 (patch) | |
| tree | 999cc75a56d86410682a1cb42e372006741ea1d5 | |
| parent | sched/core: Simplify helpers for rq clock update skip requests (diff) | |
| download | linux-317d359df95dd0cb7653d09b7fc513770590cf85.tar.xz linux-317d359df95dd0cb7653d09b7fc513770590cf85.zip | |
sched/core: Force proper alignment of 'struct util_est'
For some as yet not understood reason, Tony gets unaligned access
traps on IA64 because of:
struct util_est ue = READ_ONCE(p->se.avg.util_est);
and:
WRITE_ONCE(p->se.avg.util_est, ue);
introduced by commit:
d519329f72a6 ("sched/fair: Update util_est only on util_avg updates")
Normally those two fields should end up on an 8-byte aligned location,
but UP and RANDSTRUCT can mess that up so enforce the alignment
explicitly.
Also make the alignment on sched_avg unconditional, as it is really
about data locality, not false-sharing.
With or without this patch the layout for sched_avg on a
ia64-defconfig build looks like:
$ pahole -EC sched_avg ia64-defconfig/kernel/sched/core.o
die__process_function: tag not supported (INVALID)!
struct sched_avg {
/* typedef u64 */ long long unsigned int last_update_time; /* 0 8 */
/* typedef u64 */ long long unsigned int load_sum; /* 8 8 */
/* typedef u64 */ long long unsigned int runnable_load_sum; /* 16 8 */
/* typedef u32 */ unsigned int util_sum; /* 24 4 */
/* typedef u32 */ unsigned int period_contrib; /* 28 4 */
long unsigned int load_avg; /* 32 8 */
long unsigned int runnable_load_avg; /* 40 8 */
long unsigned int util_avg; /* 48 8 */
struct util_est {
unsigned int enqueued; /* 56 4 */
unsigned int ewma; /* 60 4 */
} util_est; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
/* size: 64, cachelines: 1, members: 9 */
};
Reported-and-Tested-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Norbert Manthey <nmanthey@amazon.de>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony <tony.luck@intel.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Fixes: d519329f72a6 ("sched/fair: Update util_est only on util_avg updates")
Link: http://lkml.kernel.org/r/20180405080521.GG4129@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | include/linux/sched.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index f228c6033832..b3d697f3b573 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -300,7 +300,7 @@ struct util_est { unsigned int enqueued; unsigned int ewma; #define UTIL_EST_WEIGHT_SHIFT 2 -}; +} __attribute__((__aligned__(sizeof(u64)))); /* * The load_avg/util_avg accumulates an infinite geometric series @@ -364,7 +364,7 @@ struct sched_avg { unsigned long runnable_load_avg; unsigned long util_avg; struct util_est util_est; -}; +} ____cacheline_aligned; struct sched_statistics { #ifdef CONFIG_SCHEDSTATS @@ -435,7 +435,7 @@ struct sched_entity { * Put into separate cache line so it does not * collide with read-mostly values above. */ - struct sched_avg avg ____cacheline_aligned_in_smp; + struct sched_avg avg; #endif }; |