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| author | Nicholas Piggin <npiggin@gmail.com> | 2022-11-26 19:59:31 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2022-12-02 17:48:50 +1100 |
| commit | 12b459a5ebf3308e718bc1dd48acb7c4cf7f1a75 (patch) | |
| tree | e2d0a72d2511fd0f86fb78b8a2e556966621c250 /arch/powerpc/include | |
| parent | 39dfc73596b48bb50cf7e4f3f54e38427dda5b4e (diff) | |
| download | linux-12b459a5ebf3308e718bc1dd48acb7c4cf7f1a75.tar.bz2 | |
powerpc/qspinlock: provide accounting and options for sleepy locks
Finding the owner or a queued waiter on a lock with a preempted vcpu is
indicative of an oversubscribed guest causing the lock to get into
trouble. Provide some options to detect this situation and have new CPUs
avoid queueing for a longer time (more steal iterations) to minimise the
problems caused by vcpu preemption on the queue.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221126095932.1234527-17-npiggin@gmail.com
Diffstat (limited to 'arch/powerpc/include')
| -rw-r--r-- | arch/powerpc/include/asm/qspinlock_types.h | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/powerpc/include/asm/qspinlock_types.h b/arch/powerpc/include/asm/qspinlock_types.h index adfeed4aa495..4766a7aa03cb 100644 --- a/arch/powerpc/include/asm/qspinlock_types.h +++ b/arch/powerpc/include/asm/qspinlock_types.h @@ -30,7 +30,7 @@ typedef struct qspinlock { * * 0: locked bit * 1-14: lock holder cpu - * 15: unused bit + * 15: lock owner or queuer vcpus observed to be preempted bit * 16: must queue bit * 17-31: tail cpu (+1) */ @@ -50,6 +50,11 @@ typedef struct qspinlock { #error "qspinlock does not support such large CONFIG_NR_CPUS" #endif +/* 0x00008000 */ +#define _Q_SLEEPY_OFFSET 15 +#define _Q_SLEEPY_BITS 1 +#define _Q_SLEEPY_VAL (1U << _Q_SLEEPY_OFFSET) + /* 0x00010000 */ #define _Q_MUST_Q_OFFSET 16 #define _Q_MUST_Q_BITS 1 |