From: Mikulas Patocka Date: Tue, 14 Jan 2014 00:13:05 +0000 (-0500) Subject: dm snapshot: use dm-bufio prefetch X-Git-Tag: v3.14-rc1~130^2~5 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=55b082e614e219fb5199a6f93e648ed35d3c96d5;p=pandora-kernel.git dm snapshot: use dm-bufio prefetch This patch modifies dm-snapshot so that it prefetches the buffers when loading the exceptions. The number of buffers read ahead is specified in the DM_PREFETCH_CHUNKS macro. The current value for DM_PREFETCH_CHUNKS (12) was found to provide the best performance on a single 15k SCSI spindle. In the future we may modify this default or make it configurable. Also, introduce the function dm_bufio_set_minimum_buffers to setup bufio's number of internal buffers before freeing happens. dm-bufio may hold more buffers if enough memory is available. There is no guarantee that the specified number of buffers will be available - if you need a guarantee, use the argument reserved_buffers for dm_bufio_client_create. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer --- Reading git-diff-tree failed