On Fri, Dec 11, 2015 at 08:01:31AM -0700, David Ahern wrote: > On 12/11/15 1:11 AM, Ingo Molnar wrote: > > > >* Namhyung Kim <namhy...@gmail.com> wrote: > > > >>IIRC David said that thread per cpu seems too much especially on a large > >>system > >>(like ~1024 cpu). [...] > > > >Too much in what fashion? For recording I think it's the fastest, most > >natural > >model - anything else will create cache line bounces. > > The intrusiveness of perf on the system under observation. I understand > there are a lot of factors that go into it.
So I can see some of that, if every cpu has its own thread then every cpu will occasionally schedule that thread. Whereas if there were less, you'd not have that. Still, I think it makes sense to implement it, we need the multi-file option anyway. Once we have that, we can also implement a per-node option, which should be a fairly simple hybrid of the two approaches. The thing is, perf-record is really struggling on big machines. And in an unrelated note, I absolutely detest --buildid being the default, it makes perf-record blow chunks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
