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    SubjectRe: 2.5 io statistics?
    Larry McVoy <> wrote:
    > Is there a writeup of the changes anywhere? I'd like to port cstat to 2.5.
    > Cstat is sort of a netstat/vmstat combo:
    > load free cach swap pgin pgou dk0 dk1 dk2 dk3 ipkt opkt int ctx usr sys idl
    > 0.00 19M 562M 48M 4.0K 12K 0 0 0 0 137 25 267 83 0 0 100
    > 0.00 18M 563M 48M 0 12K 0 0 0 0 133 22 258 77 0 1 99

    It's currently undergoing a bit of change.

    In 2.5.67 all IO activity is monitored by opening and reading
    /sys/block/hda/stat. This certainly doesn't scale when you have thousands of
    disks, so there's a patch in -mm which performs runtime aggregation of global
    stats and exposes that via /proc/diskstats.

    So if you want to monitor the "global" IO activity, you don't need to open all
    those sysfs files.

    I don't know if the aggregate disk stats patch is ready to go yet. I'm
    awaiting testing results, conversion of userspace tools, etc. I just plonked
    it in there and haven't heard anything since.

    As far as I know, neither the format of the sysfs file nor the format of
    /proc/diskstats is documented anywhere.

    Perhaps Rick can prepare a description for inclusion under Dcumentation/

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      Last update: 2005-03-22 13:34    [from the cache]
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