aboutsummaryrefslogtreecommitdiffstats
path: root/block/blk-sysfs.c
diff options
context:
space:
mode:
authorJens Axboe <jens.axboe@oracle.com>2008-09-13 20:26:01 +0200
committerJens Axboe <jens.axboe@oracle.com>2008-10-09 08:56:09 +0200
commitc7c22e4d5c1fdebfac4dba76de7d0338c2b0d832 (patch)
treeecc3d2517b3471ccc35d4cb4e3b48d4b57205061 /block/blk-sysfs.c
parent18887ad910e56066233a07fd3cfb2fa11338b782 (diff)
downloadmrst-s0i3-test-c7c22e4d5c1fdebfac4dba76de7d0338c2b0d832.tar.gz
mrst-s0i3-test-c7c22e4d5c1fdebfac4dba76de7d0338c2b0d832.tar.xz
mrst-s0i3-test-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-sysfs.c')
-rw-r--r--block/blk-sysfs.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index b9a6ed16664..21e275d7eed 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -156,6 +156,30 @@ static ssize_t queue_nomerges_store(struct request_queue *q, const char *page,
return ret;
}
+static ssize_t queue_rq_affinity_show(struct request_queue *q, char *page)
+{
+ unsigned int set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags);
+
+ return queue_var_show(set != 0, page);
+}
+
+static ssize_t
+queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
+{
+ ssize_t ret = -EINVAL;
+#if defined(CONFIG_USE_GENERIC_SMP_HELPERS)
+ unsigned long val;
+
+ ret = queue_var_store(&val, page, count);
+ spin_lock_irq(q->queue_lock);
+ if (val)
+ queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
+ else
+ queue_flag_clear(QUEUE_FLAG_SAME_COMP, q);
+ spin_unlock_irq(q->queue_lock);
+#endif
+ return ret;
+}
static struct queue_sysfs_entry queue_requests_entry = {
.attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
@@ -197,6 +221,12 @@ static struct queue_sysfs_entry queue_nomerges_entry = {
.store = queue_nomerges_store,
};
+static struct queue_sysfs_entry queue_rq_affinity_entry = {
+ .attr = {.name = "rq_affinity", .mode = S_IRUGO | S_IWUSR },
+ .show = queue_rq_affinity_show,
+ .store = queue_rq_affinity_store,
+};
+
static struct attribute *default_attrs[] = {
&queue_requests_entry.attr,
&queue_ra_entry.attr,
@@ -205,6 +235,7 @@ static struct attribute *default_attrs[] = {
&queue_iosched_entry.attr,
&queue_hw_sector_size_entry.attr,
&queue_nomerges_entry.attr,
+ &queue_rq_affinity_entry.attr,
NULL,
};