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@xxxxxxxxxxxxx> Tested-by: Srivatsa S. Bhat (VMware) <srivatsa@xxxxxxxxxxxxx> Signed-off-by: Paolo Valente <paolo.valente@xxxxxxxxxx> --- block/bfq-iosched.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) 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; -- 2.20.1
