Em Mon, Sep 18, 2017 at 10:57:08AM +0200, Jiri Olsa escreveu: > On Sun, Sep 10, 2017 at 07:23:13PM -0700, [email protected] wrote: > > From: Kan Liang <[email protected]> > > > > 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. - Arnaldo
