| Message ID | 54B04E94.3010403@kernel.dk (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | Mike Snitzer |
| Headers | show |
On Fri, Jan 09 2015 at 4:56pm -0500, Jens Axboe <axboe@kernel.dk> wrote: > On 01/09/2015 02:40 PM, Mike Snitzer wrote: > >On Fri, Jan 09 2015 at 4:11pm -0500, > >Jens Axboe <axboe@kernel.dk> wrote: > > > >> > >>Actually, try this one instead, it should be a bit more precise than > >>the first. > >> > > > >Thanks for the test patch. > > > >I'm still seeing failures that look wrong (last_tag=127 could be edge > >condition not handled properly?): > > > >[ 14.254632] __bt_get: values before for loop: last_tag=127, index=3 > >[ 14.255841] __bt_get: values after for loop: last_tag=64, index=2 > >[ 14.257036] > >[ 14.257036] bt_get: __bt_get() returned -1 > >[ 14.258051] queue_num=0, nr_tags=128, reserved_tags=0, bits_per_word=5 > >[ 14.259246] nr_free=128, nr_reserved=0 > >[ 14.259963] active_queues=0 > > > >[ 213.115997] __bt_get: values before for loop: last_tag=127, index=3 > >[ 213.117115] __bt_get: values after for loop: last_tag=96, index=3 > >[ 213.118200] > >[ 213.118200] bt_get: __bt_get() returned -1 > >[ 213.121593] queue_num=0, nr_tags=128, reserved_tags=0, bits_per_word=5 > >[ 213.123960] nr_free=128, nr_reserved=0 > >[ 213.125880] active_queues=0 > > > >[ 239.158079] __bt_get: values before for loop: last_tag=8, index=0 > >[ 239.160363] __bt_get: values after for loop: last_tag=0, index=0 > >[ 239.162896] > >[ 239.162896] bt_get: __bt_get() returned -1 > >[ 239.166284] queue_num=0, nr_tags=128, reserved_tags=0, bits_per_word=5 > >[ 239.168623] nr_free=127, nr_reserved=0 > >[ 239.170508] active_queues=0 > > Thanks for testing, can you try this one? Huh, at least now we're now seeing some nr_free=0... but the last 3 failures below look unnecessary still. E.g. the last_tag=127 case [ 13.895265] __bt_get: values before for loop: last_tag=59, index=1 [ 13.895265] __bt_get: values after for loop: last_tag=32, index=1 [ 13.895266] [ 13.895266] bt_get: __bt_get() returned -1 [ 13.895267] queue_num=0, nr_tags=128, reserved_tags=0, bits_per_word=5 [ 13.895267] nr_free=0, nr_reserved=0 [ 13.895268] active_queues=0 [ 13.895269] __bt_get: values before for loop: last_tag=0, index=0 [ 13.895270] __bt_get: values after for loop: last_tag=0, index=0 [ 13.895270] [ 13.895270] bt_get: __bt_get() returned -1 [ 13.895271] queue_num=0, nr_tags=128, reserved_tags=0, bits_per_word=5 [ 13.895272] nr_free=0, nr_reserved=0 [ 13.895272] active_queues=0 [ 13.895324] __bt_get: values before for loop: last_tag=0, index=0 [ 13.895324] __bt_get: values after for loop: last_tag=0, index=0 [ 13.895325] bt_get: __bt_get() _still_ returned -1 [ 13.895325] queue_num=0, nr_tags=128, reserved_tags=0, bits_per_word=5 [ 13.895326] nr_free=0, nr_reserved=0 [ 13.895326] active_queues=0 [ 18.931425] __bt_get: values before for loop: last_tag=127, index=3 [ 18.933317] __bt_get: values after for loop: last_tag=0, index=0 [ 18.935140] [ 18.935140] bt_get: __bt_get() returned -1 [ 18.936807] queue_num=0, nr_tags=128, reserved_tags=0, bits_per_word=5 [ 18.938772] nr_free=128, nr_reserved=0 [ 18.939927] active_queues=0 [ 489.119597] __bt_get: values before for loop: last_tag=95, index=2 [ 489.120621] __bt_get: values after for loop: last_tag=96, index=3 [ 489.121624] [ 489.121624] bt_get: __bt_get() returned -1 [ 489.122532] queue_num=0, nr_tags=128, reserved_tags=0, bits_per_word=5 [ 489.123581] nr_free=128, nr_reserved=0 [ 489.124206] active_queues=0 [ 494.705758] __bt_get: values before for loop: last_tag=127, index=3 [ 494.707797] __bt_get: values after for loop: last_tag=0, index=0 [ 494.709696] [ 494.709696] bt_get: __bt_get() returned -1 [ 494.712459] queue_num=0, nr_tags=128, reserved_tags=0, bits_per_word=5 [ 494.714403] nr_free=128, nr_reserved=0 [ 494.715955] active_queues=0 -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index 60c9d4a93fe4..4130c2bdc6c0 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -143,28 +143,31 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx, static int __bt_get_word(struct blk_align_bitmap *bm, unsigned int last_tag) { int tag, org_last_tag, end; - bool wrap = last_tag != 0; org_last_tag = last_tag; end = bm->depth; - do { -restart: - tag = find_next_zero_bit(&bm->word, end, last_tag); + while (1) { + tag = find_next_zero_bit(&bm->word, bm->depth, last_tag); if (unlikely(tag >= end)) { /* * We started with an offset, start from 0 to * exhaust the map. */ - if (wrap) { - wrap = false; + if (org_last_tag) { end = org_last_tag; - last_tag = 0; - goto restart; + last_tag = org_last_tag = 0; + continue; } return -1; } + + if (!test_and_set_bit(tag, &bm->word)) + break; + last_tag = tag + 1; - } while (test_and_set_bit(tag, &bm->word)); + if (last_tag >= bm->depth - 1) + last_tag = 0; + } return tag; } @@ -199,9 +202,13 @@ static int __bt_get(struct blk_mq_hw_ctx *hctx, struct blk_mq_bitmap_tags *bt, goto done; } - last_tag = 0; - if (++index >= bt->map_nr) + index++; + last_tag = (index << bt->bits_per_word); + + if (index >= bt->map_nr) { index = 0; + last_tag = 0; + } } *tag_cache = 0;