On 09/03/2014 02:33 PM, Alexander Gordeev wrote: > Fair share of tags is number of tags diveded on number > of users. Not sure why it is different. > > Signed-off-by: Alexander Gordeev <agord...@redhat.com> > Cc: Jens Axboe <ax...@kernel.dk> > --- > block/blk-mq-tag.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c > index d1eb579..1b9c949 100644 > --- a/block/blk-mq-tag.c > +++ b/block/blk-mq-tag.c > @@ -127,7 +127,7 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx > *hctx, > /* > * Allow at least some tags > */ > - depth = max((bt->depth + users - 1) / users, 4U); > + depth = max(bt->depth / users, 4U); > return atomic_read(&hctx->nr_active) < depth;
It's normal rounding, you'll round down otherwise. Say you have a tag depth of 31 (SATA), and 4 active users. Your change would make that 7 tags per user, leaving 3 idle. If you round up, you end up with 8 tags instead. That will potentially just leave some sleeping for a new tag, but at least you'll exhaust the space. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
