Linus,
Please pull "hwlat", the hardware latency detector for 2.6.31.
Patches can be pulled from:
git://git.kernel.org/pub/scm/linux/kernel/git/jcm/linux-2.6-hwlat.git for-linus
Jon Masters (2):
hwlat_detector: A system hardware latency detector
hwlat_detector: include linux/delay.h in hwlat_detector
Documentation/hwlat_detector.txt | 64 ++
MAINTAINERS | 9 +
drivers/misc/Kconfig | 28 +
drivers/misc/Makefile | 1 +
drivers/misc/hwlat_detector.c | 1208 ++++++++++++++++++++++++++++++++++++++
5 files changed, 1310 insertions(+), 0 deletions(-)
create mode 100644 Documentation/hwlat_detector.txt
create mode 100644 drivers/misc/hwlat_detector.c
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. Has this been in -next?
Discussed on lkml? How does it work? What does it do?
Thanks,
Linus
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.