os/bluestore: separate finisher for deferred_try_submit #17409
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Reusing finishers[0], which is used for completions back into the OSD, is deadlock-prone: the OSD code might block trying to submit new IO or while waiting for some other bluestore work to complete. Fixes: http://tracker.ceph.com/issues/21207 Signed-off-by: Sage Weil <sage@redhat.com>
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LGTM, but we are adding many threads into bluestore IO path, which adds more context switching overhead. |
xiexingguo
approved these changes
Sep 1, 2017
there were a couple of PRs related to this issue, and I think this is fine as long as it turns out to be the right and hopefully final cure... |
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Yeah, i agree, but just wanted to be little cautious on adding more threads and context switches. |
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This is an exceptional case.. it only comes up during split or when the deferred io throttles are saturated, and is only there to make sure the pipeline doesn't stall. I don't think it will be a problem. |
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Reusing finishers[0], which is used for completions back into the OSD,
is deadlock-prone: the OSD code might block trying to submit new IO or
while waiting for some other bluestore work to complete.
Fixes: http://tracker.ceph.com/issues/21207
Signed-off-by: Sage Weil sage@redhat.com