On Mon, Sep 18, 2017 at 10:01:00AM -0300, Arnaldo Carvalho de Melo wrote: > Em Mon, Sep 18, 2017 at 10:57:08AM +0200, Jiri Olsa escreveu: > > On Sun, Sep 10, 2017 at 07:23:13PM -0700, kan.li...@intel.com wrote: > > > From: Kan Liang <kan.li...@intel.com> > > > > > > The patch series intends to fix the severe performance issue in > > > Knights Landing/Mill, when monitoring in heavy load system. > > > perf top costs a few minutes to show the result, which is > > > unacceptable. > > > With the patch series applied, the latency will reduces to > > > several seconds. > > > > > > machine__synthesize_threads and perf_top__mmap_read costs most of > > > the perf top time (> 99%). > > > > looks like this patchset adds locking into code paths > > used by other single threaded tools and that might > > be bad for them as noted by Andi in here: > > > > https://marc.info/?l=linux-kernel&m=149031672928989&w=2 > > > > he proposed solution and it was changed&posted by Arnaldo in here: > > > > https://marc.info/?l=linux-kernel&m=149132267410294&w=2 > > > > but looks like it never got merged > > > > could you please add this or similar code before you add the > > locking code/overhead in? > > I'm rehashing that patch and adding it on top of what is in my perf/core > branch, will push soon, for now you can take a look at tmp.perf/core.
checked the code.. one nit, could we have single threaded by default? only one command is multithreaded atm, it could call perf_set_multihreaded instead of all current related commands call perf_set_singlethreaded other than that it looks ok thanks, jirka