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authorDan Williams <dan.j.williams@intel.com>2011-07-23 14:44:25 -0400
committerJens Axboe <jaxboe@fusionio.com>2011-07-23 14:44:25 -0400
commit5757a6d76cdf6dda2a492c09b985c015e86779b1 (patch)
tree6356a6353639eb473dd917a1b2062f9e7e20de22 /block/blk-softirq.c
parentef3230880abd36553ab442363d3c9a0661f00769 (diff)
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-softirq.c')
-rw-r--r--block/blk-softirq.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/block/blk-softirq.c b/block/blk-softirq.c
index ee9c21602228..475fab809a80 100644
--- a/block/blk-softirq.c
+++ b/block/blk-softirq.c
@@ -103,22 +103,25 @@ static struct notifier_block __cpuinitdata blk_cpu_notifier = {
103 103
104void __blk_complete_request(struct request *req) 104void __blk_complete_request(struct request *req)
105{ 105{
106 int ccpu, cpu, group_cpu = NR_CPUS;
106 struct request_queue *q = req->q; 107 struct request_queue *q = req->q;
107 unsigned long flags; 108 unsigned long flags;
108 int ccpu, cpu, group_cpu;
109 109
110 BUG_ON(!q->softirq_done_fn); 110 BUG_ON(!q->softirq_done_fn);
111 111
112 local_irq_save(flags); 112 local_irq_save(flags);
113 cpu = smp_processor_id(); 113 cpu = smp_processor_id();
114 group_cpu = blk_cpu_to_group(cpu);
115 114
116 /* 115 /*
117 * Select completion CPU 116 * Select completion CPU
118 */ 117 */
119 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) && req->cpu != -1) 118 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) && req->cpu != -1) {
120 ccpu = req->cpu; 119 ccpu = req->cpu;
121 else 120 if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags)) {
121 ccpu = blk_cpu_to_group(ccpu);
122 group_cpu = blk_cpu_to_group(cpu);
123 }
124 } else
122 ccpu = cpu; 125 ccpu = cpu;
123 126
124 if (ccpu == cpu || ccpu == group_cpu) { 127 if (ccpu == cpu || ccpu == group_cpu) {