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    SubjectRe: [PATCH] backing dev unplugging
    >>>>> On Wed, 10 Mar 2004 15:54:19 -0800, Andrew Morton <> said:

    Andrew> (Jesse Barnes) wrote:
    >> -------------------------------------
    >> w/Jens' patch: ~47149 I/Os per second

    Andrew> Happier.

    >> [root@revenue sio]# readprofile -m /root/ | sort -nr +2
    >> | head -20 181993 default_idle 5687.2812 624772 snidle 1627.0104
    >> 209129 cpu_idle 435.6854 4755 dio_bio_end_io 12.3828 6593
    >> scsi_end_request 12.1195 435 ia64_spinlock_contention 6.7969 2959
    >> sn_dma_flush 4.4033

    Andrew> Do you know where that spinlock contention is coming from?

    Andrew> (We have a little patch for x86 which places the spinning
    Andrew> code inline in the caller of spin_lock() so it appears
    Andrew> nicely in profiles.)

    And real men use profiling tools that provide a call-graph, so this
    hack isn't necessary... ;-)

    Jesse, if you want to try q-tools and need some help in getting the
    per-CPU results merged, let me know (it's something that's planned for
    a future release, but there is only so many hours in a day so this
    hasn't been done yet).

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