From: Tejun Heo Date: Wed, 9 Jan 2013 16:05:13 +0000 (-0800) Subject: cfq-iosched: collect stats from dead cfqgs X-Git-Tag: v3.9-rc1~44^2~12^2~1 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0b39920b5f9f3ad37dd259bfa2e9cbca33475b28;p=pandora-kernel.git cfq-iosched: collect stats from dead cfqgs To support hierarchical stats, it's necessary to remember stats from dead children. Add cfqg->dead_stats and make a dying cfqg transfer its stats to the parent's dead-stats. The transfer happens form ->pd_offline_fn() and it is possible that there are some residual IOs completing afterwards. Currently, we lose these stats. Given that cgroup removal isn't a very high frequency operation and the amount of residual IOs on offline are likely to be nil or small, this shouldn't be a big deal and the complexity needed to handle residual IOs - another callback and rather elaborate synchronization to reach and lock the matching q - doesn't seem justified. Signed-off-by: Tejun Heo Acked-by: Vivek Goyal --- Reading git-diff-tree failed