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authorDan Williams2011-07-23 13:44:25 -0500
committerJens Axboe2011-07-23 13:44:25 -0500
commit5757a6d76cdf6dda2a492c09b985c015e86779b1 (patch)
tree6356a6353639eb473dd917a1b2062f9e7e20de22 /block/blk-sysfs.c
parentef3230880abd36553ab442363d3c9a0661f00769 (diff)
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block: strict rq_affinity
Some systems benefit from completions always being steered to the strict requester cpu rather than the looser "per-socket" steering that blk_cpu_to_group() attempts by default. This is because the first CPU in the group mask ends up being completely overloaded with work, while the others (including the original submitter) has power left to spare. Allow the strict mode to be set by writing '2' to the sysfs control file. This is identical to the scheme used for the nomerges file, where '2' is a more aggressive setting than just being turned on. echo 2 > /sys/block/<bdev>/queue/rq_affinity Cc: Christoph Hellwig <hch@infradead.org> Cc: Roland Dreier <roland@purestorage.com> Tested-by: Dave Jiang <dave.jiang@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'block/blk-sysfs.c')
-rw-r--r--block/blk-sysfs.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index d935bd859c8..0ee17b5e7fb 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -244,8 +244,9 @@ static ssize_t queue_nomerges_store(struct request_queue *q, const char *page,
244static ssize_t queue_rq_affinity_show(struct request_queue *q, char *page) 244static ssize_t queue_rq_affinity_show(struct request_queue *q, char *page)
245{ 245{
246 bool set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags); 246 bool set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags);
247 bool force = test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags);
247 248
248 return queue_var_show(set, page); 249 return queue_var_show(set << force, page);
249} 250}
250 251
251static ssize_t 252static ssize_t
@@ -257,10 +258,14 @@ queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
257 258
258 ret = queue_var_store(&val, page, count); 259 ret = queue_var_store(&val, page, count);
259 spin_lock_irq(q->queue_lock); 260 spin_lock_irq(q->queue_lock);
260 if (val) 261 if (val) {
261 queue_flag_set(QUEUE_FLAG_SAME_COMP, q); 262 queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
262 else 263 if (val == 2)
263 queue_flag_clear(QUEUE_FLAG_SAME_COMP, q); 264 queue_flag_set(QUEUE_FLAG_SAME_FORCE, q);
265 } else {
266 queue_flag_clear(QUEUE_FLAG_SAME_COMP, q);
267 queue_flag_clear(QUEUE_FLAG_SAME_FORCE, q);
268 }
264 spin_unlock_irq(q->queue_lock); 269 spin_unlock_irq(q->queue_lock);
265#endif 270#endif
266 return ret; 271 return ret;