Messages in this thread | | | Subject | Re: [PULL] hardware latency detector | From | Jon Masters <> | Date | Thu, 18 Jun 2009 21:32:20 -0400 |
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On Thu, 2009-06-18 at 18:25 -0700, Linus Torvalds wrote: > > On Thu, 18 Jun 2009, Jon Masters wrote: > > > > Please pull "hwlat", the hardware latency detector for 2.6.31. > > I really want to know more before I pull.
Ok.
> Has this been in -next?
No, it hasn't. But it has been tested quite extensively by a number of people and is currently in the -rt tree.
> Discussed on lkml?
Yes. I posted an RFC patch back when it was called the SMI detector, then a patch last week with the new generic name of hardware latency detector (at Ingo's suggestion of renaming).
> How does it work?
It started as an SMI detector. Basically, when this module is loaded and enabled, it will grab all CPUs in periodic calls to stop_machine and sit in a configurable loop, looking for unexplainable latencies. Doing it this way allows us to look for something stealing the CPU from Linux without the kernel knowing - we report the statistics via debugfs.
Hope that helps! Thanks Linus!
Jon.
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