From: Jens Axboe Date: Fri, 9 May 2014 19:41:15 +0000 (-0600) Subject: blk-mq: use sparser tag layout for lower queue depth X-Git-Tag: omap-for-v3.16/fixes-against-rc1~39^2~49^2~41^2~4 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=59d13bf5f57ded658c872fa22276f75ab8f12841;p=pandora-kernel.git blk-mq: use sparser tag layout for lower queue depth For best performance, spreading tags over multiple cachelines makes the tagging more efficient on multicore systems. But since we have 8 * sizeof(unsigned long) tags per cacheline, we don't always get a nice spread. Attempt to spread the tags over at least 4 cachelines, using fewer number of bits per unsigned long if we have to. This improves tagging performance in setups with 32-128 tags. For higher depths, the spread is the same as before (BITS_PER_LONG tags per cacheline). Signed-off-by: Jens Axboe --- Reading git-diff-tree failed