On Mon, 18 Nov 2013 19:17:37 -0700, David Ahern wrote: > On 11/18/13, 7:13 PM, Namhyung Kim wrote: >> 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..) > > you don't need the cycles. faults by itself works. Each event contains > 2 pages of data in the sample. With mmap-based output a single > sample (1 page fault in any process) generates 2-3 page faults by perf > which cause 2-3 >8k samples to be generated, which generates faults, > ....
But after perf touches all pages in ring-buffer and stack, it won't generate page-faults for itself anymore, right? Hmm.. thinking it again, perf has all ring-buffer pages in memory when mmap() called, right? If so why not doing something like MAP_POPULATE so that it doesn't need to generate minor-faults? Thanks, Namhyung -- 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/