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    SubjectRe: [PATCH] 2.6.0-test4 -- add context switch counters
    >> Command exited with non-zero status 100 Command being timed:
    >> "apt-get update" User time (seconds): 0.01 System time (seconds):
    >> 0.00 Percent of CPU this job got: 6% Elapsed (wall clock) time
    >> (h:mm:ss or m:ss): 0:00.32 Average shared text size (kbytes): 0
    >> Average unshared data size (kbytes): 0 Average stack size (kbytes):
    >> 0 Average total size (kbytes): 0 The averages might be nice...

    William> The averages themselves aren't reported with getrusage(),
    William> only direct usage measurements. Presumably luserspace
    William> computes the averages itself. i.e. the counters are all for
    William> non-average versions of these stats and (because we're seeing
    William> all 0's) are not reported at all.

    Yes, the kernel is (supposed) to calculate the integral over time of
    the memory sizes; user space divides these integrals by elapsed time
    to get averages.

    To calculate these you need a timestamp for last change, and a set of
    Then code to update all the counters every time one of the sizes
    change (otherwise you need a timestamp for each counter) by adding
    current_size*(current_time - last_change_time) to each counter.

    William> On Tue, Aug 26, 2003 at 06:29:14PM -0700, Mike Fedyk wrote:
    >> Maximum resident set size (kbytes): 0 But the maximum would allow
    >> any polling app to do its polling less often. As well as the
    >> averages above... Average resident set size (kbytes): 0 Major
    >> (requiring I/O) page faults: 320 Minor (reclaiming a frame) page
    >> faults: 21

    William> The fault counters are vaguely bogus when threads are
    William> involved. There's a comment alluding to that nearby.

    The fault counters are incorrect anyway --- faults satisfied from the
    page cache are counted as major faults, whereas we expect only faults
    that sleep for disk I/O to be counted as major faults.

    William> On Tue, Aug 26, 2003 at 06:29:14PM -0700, Mike Fedyk wrote:
    >> Swaps: 0 Counting swaps would be nice too.

    William> This already has two counters in the task_t (no, I will not
    William> use Finnish Hungarian notation in my general posts) that are
    William> 100% unused. Probably the only thing preventing slab poison
    William> from showing up there outright is the whole task_t copy in
    William> kernel/fork.c and the bss zeroing for init_task.

    It's unclear what `swaps' are in Linux. Traditionally, this rusage
    field was the number of complete swapouts --- I'm not sure what the
    equivalent is when processes are not swapped out holus-bolus, but are
    paged gradually.

    William> On Tue, Aug 26, 2003 at 06:29:14PM -0700, Mike Fedyk wrote:
    >> File system inputs: 0 File system outputs: 0 Socket messages sent:
    >> 0 Socket messages received: 0 Signals delivered: 0 Yes, yes, yes.

    William> These would be easy to set up, they just need counters and
    William> the ticking of the counters dropped in.

    It's on my list of things to do, if not soon, then I'm hoping for a
    summer student to do some of this stuff.

    Dr Peter Chubb peterc AT
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