On Mon, 18 Nov 2013 17:34:49 -0700, David Ahern wrote: > On 11/18/13, 5:24 PM, Namhyung Kim wrote: >>>>> What now? Can we add the mmap path as an option? >>>> >>>> I'd say an option is always a possibility, but someone please try >>>> what happens if you use stupid large events (dwarf stack copies) on >>>> PERF_COUNT_SW_PAGE_FAULTS (.period=1) while recording with mmap(). >>>> >>>> The other option is to simply disallow PERF_SAMPLE_STACK_USER for >>>> that event. >>>> >>>> Personally I think 8k copies for every event are way stupid anyway, >>>> that's a metric ton of data at a huge cost. >>> >>> Well, with 1 khz sampling of a single threaded workload it's 8MB per >>> second - that's 80 MB for 10 seconds profiling - not the end of the >>> world. >> >> We now use 4 khz sampling frequency by default, just FYI. :) > > I think Peter is asking about: > perf record -e faults -c 1 --call-graph dwarf,8192 -a -- sleep 1
I think it should be perf record -e cycles -F 4000 -e faults -c 1 --call-graph dwarf,8192 -a -- sleep 1 (at least to generate the feedback spiral more efficiently..) Well, I know that we don't support this now. But wouldn't it make sense to support this kind of thing? Thanks, Namhyung -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
