| Message ID | 1489065402-14757-10-git-send-email-sagi@grimberg.me (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
On 03/09/2017 02:16 PM, Sagi Grimberg wrote: > It doesn't really make sense to do selective polling > because we never care about specific IOs. Non selective > polling can actually help by doing some useful work > while we're submitting a command. > > We ask for a batch of (magic) 4 completions which looks > like a decent network<->backend proportion, if less are > available we'll see less. > > Signed-off-by: Sagi Grimberg <sagi@grimberg.me> > --- Just out of curiosity, how did you come up with the magic 4? Thanks, Johannes
diff --git a/drivers/nvme/target/io-cmd.c b/drivers/nvme/target/io-cmd.c index 4195115c7e54..8e4fd7ca4a8a 100644 --- a/drivers/nvme/target/io-cmd.c +++ b/drivers/nvme/target/io-cmd.c @@ -46,7 +46,6 @@ static void nvmet_execute_rw(struct nvmet_req *req) struct scatterlist *sg; struct bio *bio; sector_t sector; - blk_qc_t cookie; int op, op_flags = 0, i; if (!req->sg_cnt) { @@ -85,16 +84,17 @@ static void nvmet_execute_rw(struct nvmet_req *req) bio_set_op_attrs(bio, op, op_flags); bio_chain(bio, prev); - cookie = submit_bio(prev); + submit_bio(prev); } sector += sg->length >> 9; sg_cnt--; } - cookie = submit_bio(bio); + submit_bio(bio); - blk_mq_poll(bdev_get_queue(req->ns->bdev), cookie); + /* magic 4 is what we are willing to grab before we return */ + blk_mq_poll_batch(bdev_get_queue(req->ns->bdev), 4); } static void nvmet_execute_flush(struct nvmet_req *req)
It doesn't really make sense to do selective polling because we never care about specific IOs. Non selective polling can actually help by doing some useful work while we're submitting a command. We ask for a batch of (magic) 4 completions which looks like a decent network<->backend proportion, if less are available we'll see less. Signed-off-by: Sagi Grimberg <sagi@grimberg.me> --- drivers/nvme/target/io-cmd.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)