Messages in this thread | | | Date | Mon, 22 Aug 2005 10:50:53 -0700 | From | Andrew Morton <> | Subject | Re: CONFIG_PRINTK_TIME woes |
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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. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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