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authorTejun Heo <tj@kernel.org>2013-05-14 22:52:32 +0200
committerTejun Heo <tj@kernel.org>2013-05-14 22:52:32 +0200
commit6a525600ffeb9e0d6cbbebda49eb89d6d3408c2b (patch)
treef4ced3b39162c54ecf12f0171b781e60d54e4a7c /lib/dec_and_lock.c
parentblk-throttle: relocate throtl_schedule_delayed_work() (diff)
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blk-throttle: remove pointless throtl_nr_queued() optimizations
throtl_nr_queued() is used in several places to avoid performing certain operations when the throtl_data is empty. This usually is useless as those paths usually aren't traveled if there's no bio queued. * throtl_schedule_delayed_work() skips scheduling dispatch work item if @td doesn't have any bios queued; however, the only case it can be called when @td is empty is from tg_set_conf() which isn't something we should be optimizing for. * throtl_schedule_next_dispatch() takes a quick exit if @td is empty; however, right after that it triggers BUG if the service tree is empty. The two conditions are equivalent and it can just test @st->count for the quick exit. * blk_throtl_dispatch_work_fn() skips dispatch if @td is empty. This work function isn't usually invoked when @td is empty. The only possibility is from tg_set_conf() and when it happens the normal dispatching path can handle empty @td fine. No need to add special skip path. This patch removes the above three unnecessary optimizations, which leave throtl_log() call in blk_throtl_dispatch_work_fn() the only user of throtl_nr_queued(). Remove throtl_nr_queued() and open code it in throtl_log(). I don't think we need td->nr_queued[] at all. Maybe we can remove it later. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com>
Diffstat (limited to 'lib/dec_and_lock.c')
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