Hello,
this patch series restores regression in dbench for large number of processes
that was introduced by c65e6fd460b4 ("bfq: Do not let waker requests skip
proper accounting"). The detailed explanation is in the first patch but the
culprit in the end was that with large number of dbench clients it often
happened that flush worker bfqq replaced jbd2 bfqq as a waker of the bfqq
shared by dbench clients and that resulted in lot of idling and reduced
throughput.
The first two patches in this series improve the waker detection, the other
two are just cleanups I've spotted when working on the code.
I've tested the patches and they don't seem to cause regression for other
workloads.
Honza
