Messages in this thread | | | Date | Thu, 28 Jun 2012 12:12:53 +0800 | Subject | Re: perf support user-space hw_breakpoint? | From | Jovi Zhang <> |
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Hi,
On Thu, Jun 28, 2012 at 10:20 AM, Namhyung Kim <namhyung@kernel.org> wrote: > On Thu, 28 Jun 2012 09:02:02 +0800, Jovi Zhang wrote: >> On Mon, Jun 25, 2012 at 4:26 PM, Namhyung Kim <namhyung@kernel.org> wrote: >>> BTW, when I perf record on a hwbp, it failed with ENOSPC. >>> I guess it's because each per-task-per-cpu event tried to >>> create an event so it'd get more than supported by h/w. >>> The strace told me that the fifth call to perf_event_open >>> failed on my 6-core machine. >>> >> I have same result as you in my linux box. >> This should be a bug cause by commit d1cb9f(perf target: Add uses_mmap field) >> >> Namhyung, How about below patch? >> > > NAK. This uses_mmap field is needed to setup per-task-per-cpu events for > perf record (mostly). Without it, perf suffered from severe scalability > issues. Maybe we can change it not to create per-task-per-cpu events iff > for hwbp events only, but I'm not sure it's the right thing. > > Thanks, > Namhyung > perf tool create cpumaps and threadmaps for evlist, not for evsel, this means we cannot easily create a dummy cpumaps for hwbp event even when evlist include hwbp type evsel.
Any ideas?
.jovi
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