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    SubjectRe: [patch 0/3] j_state_lock, j_list_lock, remove-bitlocks
    Ingo Molnar <mingo@elte.hu> wrote:
    >
    >
    > * Andrew Morton <akpm@osdl.org> wrote:
    >
    > > I forget how much of the 1000% came from that, but it was quite a lot.
    > >
    > > Removing the BKL was the first step. That took the context switch
    > > rate under high load from ~10,000/sec up to ~300,000/sec. Because the
    > > first thing a CPU hit on entry to the fs was then a semaphore.
    > > Performance rather took a dive.
    > >
    > > Of course the locks also became much finer-grained, so the contention
    > > opportunities lessened. But j_list_lock and j_state_lock have fs-wide
    > > scope, so I'd expect the context switch rate to go up quite a lot
    > > again.
    > >
    > > The hold times are short, and a context switch hurts rather ore than a
    > > quick spin.
    >
    > which particular workload was this - dbench? (I can try PREEMPT_RT on an
    > 8-way, such effects will show up tenfold.)
    >

    Oh gee, that was back in the days when Martin was being useful. SDET, I
    think.

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