Questions about when we take counter measurements, reset, etc
jones.chris.g at gmail.com
Mon Oct 13 16:40:00 PDT 2014
On Fri, Oct 3, 2014 at 5:18 PM, Kyle Huey <me at kylehuey.com> wrote:
> As an alternative, I starting looking into what it would take to move
> to just using absolute counter values everywhere, and then we could
> throw away caching/resetting/etc entirely. Did cjones imagine when he
> filed #
> 803 that we would switch to using
> PERF_EVENT_IOC_PERIOD to
> reset the signalling mechanism?
I looked at using REFRESH in #599. Unfortunately, I don't remember much
more beyond what I wrote in that issue. I don't recall reading about
> The man page is a little
> concerning, stating that "Since ... Linux 3.14, the new period takes
> effect immediately. On older kernels, the new period did not take
> effect until after the next overflow". The latter could be a problem,
> hence my earlier email about the kernel version. I hacked up using
> IOC_PERIOD and it passes most but not all of the tests. Upgrading my
> kernel to 3.14 to see if that fixes the rest was a bit too much for 4
> pm on a Friday.
I don't have qualms about bumping up the minimum kernel version if it buys
us something significant. We've already done that twice.
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the rr-dev