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| author | Jens Axboe <jens.axboe@oracle.com> | 2008-09-13 20:26:01 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2008-10-09 08:56:09 +0200 |
| commit | c7c22e4d5c1fdebfac4dba76de7d0338c2b0d832 (patch) | |
| tree | ecc3d2517b3471ccc35d4cb4e3b48d4b57205061 /block/blk.h | |
| parent | 18887ad910e56066233a07fd3cfb2fa11338b782 (diff) | |
| download | lwn-c7c22e4d5c1fdebfac4dba76de7d0338c2b0d832.tar.gz lwn-c7c22e4d5c1fdebfac4dba76de7d0338c2b0d832.zip | |
block: add support for IO CPU affinity
This patch adds support for controlling the IO completion CPU of
either all requests on a queue, or on a per-request basis. We export
a sysfs variable (rq_affinity) which, if set, migrates completions
of requests to the CPU that originally submitted it. A bio helper
(bio_set_completion_cpu()) is also added, so that queuers can ask
for completion on that specific CPU.
In testing, this has been show to cut the system time by as much
as 20-40% on synthetic workloads where CPU affinity is desired.
This requires a little help from the architecture, so it'll only
work as designed for archs that are using the new generic smp
helper infrastructure.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/blk.h')
| -rw-r--r-- | block/blk.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/block/blk.h b/block/blk.h index c79f30e1df52..de74254cb916 100644 --- a/block/blk.h +++ b/block/blk.h @@ -59,4 +59,16 @@ static inline int queue_congestion_off_threshold(struct request_queue *q) #endif /* BLK_DEV_INTEGRITY */ +static inline int blk_cpu_to_group(int cpu) +{ +#ifdef CONFIG_SCHED_MC + cpumask_t mask = cpu_coregroup_map(cpu); + return first_cpu(mask); +#elif defined(CONFIG_SCHED_SMT) + return first_cpu(per_cpu(cpu_sibling_map, cpu)); +#else + return cpu; +#endif +} + #endif |