From: Jens Axboe Date: Thu, 29 May 2014 15:53:32 +0000 (-0600) Subject: block: add queue flag for disabling SG merging X-Git-Tag: omap-for-v3.16/fixes-against-rc1~39^2~49^2~8 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=05f1dd5315217398fc8d122bdee80f96a9f21274;p=pandora-kernel.git block: add queue flag for disabling SG merging If devices are not SG starved, we waste a lot of time potentially collapsing SG segments. Enough that 1.5% of the CPU time goes to this, at only 400K IOPS. Add a queue flag, QUEUE_FLAG_NO_SG_MERGE, which just returns the number of vectors in a bio instead of looping over all segments and checking for collapsible ones. Add a BLK_MQ_F_SG_MERGE flag so that drivers can opt-in on the sg merging, if they so desire. Signed-off-by: Jens Axboe --- Reading git-diff-tree failed