Messages in this thread | | | Date | Thu, 03 Mar 2011 07:33:24 -0700 | From | David Ahern <> | Subject | Re: [PATCH 3/6] perf record: add time-of-day option |
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On 03/03/2011 01:51 AM, Ingo Molnar wrote: > > * David Ahern <daahern@cisco.com> wrote: > >>> How does all that deal with CLOCK_REALTIME being affected by NTP and >>> settimeofday? Not really, as far as I can tell. It somehow works, but >>> that depends on the frequency of your event injection. >> >> It is sampled at some periodic rate to get NTP changes. Right now it is >> hardcoded at once an hour. The frequency option can be added to the >> --tod parameter. > > As Thomas mentioned, we probably need something more complete than that.
Just responded to Thomas' email with a simpler proposal than munging on tracepoints and trying to track time-of-day implicitly.
> Still your approach is obviously useful and i'd like to stress that explicitly. Have
Thanks for stating that.
> you considered another related feature, feeding printk lines as special 'string > events' into the perf ringbuffer? > > It would round up your scheme very nicely: that way you'd have a single, global, > GTOD-correlated event store/flow for basically every system event you might be > interested in. You could switch events (and tracepoints) on/off based on need, > controlling the type and rate of information in a very finegrained way. > > If the printk approach works out i'd even suggest that such a facility would need a > separate tool within perf: 'perf syslog' or 'perf log'. It would heavily reuse > perf-script and other perf internal facilities, obviously - but you would not be > tied to any particular sub-tool implementation. > > EDAC type events could feed into this as well, giving the tool a broader 'system > health' aspect as well, beyond the 'system performance analysis' aspect.
I can look into it (as time allows) once I get the dumping of software events done.
David
> > Thanks, > > Ingo
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