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    SubjectRe: CONFIG_PRINTK_TIME woes
    tony.luck@intel.com wrote:
    >
    > At the other extreme ... the current use of sched_clock() with
    > potentially nano-second resolution is way over the top. Logging
    > to a serial console at 115200 a typical line from printk will take
    > 2-4 milli-seconds to print ... so there would seem to be little
    > benefit from a sub-millisecond resolution (in fact at 250HZ jiffies
    > are on the ragged edge of being good enough).
    >
    > If that isn't sufficient ... it should be possible to make a cut-down,
    > lockless version of do_gettimeofday that meets Andrew's suggestion
    > of good resolution with occasional theoretical weirdness. But before
    > we go there ... I'd like to hear whether there are usage models that
    > really need better resolution than jiffies can provide?

    I think so. Say you're debugging or performance tuning filesystem requests
    and I/O completions, etc. You disable the console with `dmesg -n', run the
    test then do `dmesg -s 1000000 > foo'. Having somewhat-sub-millisecond
    timestamping in the resulting trace is required.
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