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authorPaolo Valente <paolo.valente@linaro.org>2019-06-25 07:12:45 +0200
committerJens Axboe <axboe@kernel.dk>2019-06-25 09:07:34 -0600
commit24792ad01cb659c8b5899de2af6e8ca250f93df3 (patch)
treeccb4a16c5352a4334c88e2ec647e49c66947857f /block
parentdb599f9ed9bd31b018b6c48ad7c6b21d5b790ecf (diff)
downloadlinux-24792ad01cb659c8b5899de2af6e8ca250f93df3.tar.bz2
block, bfq: update base request service times when possible
I/O injection gets reduced if it increases the request service times of the victim queue beyond a certain threshold. The threshold, in its turn, is computed as a function of the base service time enjoyed by the queue when it undergoes no injection. As a consequence, for injection to work properly, the above base value has to be accurate. In this respect, such a value may vary over time. For example, it varies if the size or the spatial locality of the I/O requests in the queue change. It is then important to update this value whenever possible. This commit performs this update. Reported-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu> Tested-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/bfq-iosched.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 05041f84b8da..62442083b147 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -5496,7 +5496,18 @@ static void bfq_update_inject_limit(struct bfq_data *bfqd,
* start trying injection.
*/
bfqq->inject_limit = max_t(unsigned int, 1, old_limit);
- }
+ } else if (!bfqd->rqs_injected && bfqd->rq_in_driver == 1)
+ /*
+ * No I/O injected and no request still in service in
+ * the drive: these are the exact conditions for
+ * computing the base value of the total service time
+ * for bfqq. So let's update this value, because it is
+ * rather variable. For example, it varies if the size
+ * or the spatial locality of the I/O requests in bfqq
+ * change.
+ */
+ bfqq->last_serv_time_ns = tot_time_ns;
+
/* update complete, not waiting for any request completion any longer */
bfqd->waited_rq = NULL;