From: Jaegeuk Kim Date: Wed, 2 Apr 2014 06:34:36 +0000 (+0900) Subject: f2fs: introduce f2fs_issue_flush to avoid redundant flush issue X-Git-Tag: v3.15-rc1~62^2~2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6b4afdd794783fe515b50838aa36591e3feea990;p=pandora-kernel.git f2fs: introduce f2fs_issue_flush to avoid redundant flush issue Some storage devices show relatively high latencies to complete cache_flush commands, even though their normal IO speed is prettry much high. In such the case, it needs to merge cache_flush commands as much as possible to avoid issuing them redundantly. So, this patch introduces a mount option, "-o flush_merge", to mitigate such the overhead. If this option is enabled by user, F2FS merges the cache_flush commands and then issues just one cache_flush on behalf of them. Once the single command is finished, F2FS sends a completion signal to all the pending threads. Note that, this option can be used under a workload consisting of very intensive concurrent fsync calls, while the storage handles cache_flush commands slowly. Signed-off-by: Jaegeuk Kim --- Reading git-diff-tree failed