Hi, On 18.07.2017 14:33, Alexander Shishkin wrote: > Alexey Budankov <alexey.budan...@linux.intel.com> writes: > >> Hi, > > Hi, > >> Are there any new comments so far? Could you please suggest further steps >> forward? > > Apparently the patches are not threaded, so one needs to fish them out > one by one in order to review.
Thanks for feedback. The BKM in this case is just to keep subject unchanged, right? > >> On 10.07.2017 16:03, Alexey Budankov wrote: >>> perf/core: complete replace of lists by rb trees for pinned and >>> flexible groups at perf_event_context > > No need to duplicate the subject line here. Also, it can be more concise > than this like "perf: Replace context's pinned/flexible lists with trees". > >>> By default, the userspace perf tool opens per-cpu task-bound events >>> when sampling, so for N logical events requested by the user, the tool >>> will open N * NR_CPUS events. >>> >>> In the kernel, we mux events with a hrtimer, periodically rotating the >>> flexible group list and trying to schedule each group in turn. We skip >>> groups whose cpu filter doesn't match. So when we get unlucky, we can >>> walk N * (NR_CPUS - 1) groups pointlessly for each hrtimer invocation. >>> >>> This has been observed to result in significant overhead when running >>> the STREAM benchmark on 272 core Xeon Phi systems. >>> >>> One way to avoid this is to place our events into an rb tree sorted by >>> CPU filter, so that our hrtimer can skip to the current CPU's >>> list and ignore everything else. > > It looks like these 4 paragraphs are repeated in every patch. > >>> This patch implements complete replacement of lists by rb trees for >>> pinned and flexible groups. > > And this is the actually informative part. > >>> The patch set was tested on Xeon Phi using perf_fuzzer and tests >>> from here: https://github.com/deater/perf_event_tests > > Although this is also useful. > >>> The full patch set (v1-4) is attached for convenience. >>> >>> Branch revision: >>> * perf/core 007b811b4041989ec2dc91b9614aa2c41332723e >>> Merge tag 'perf-core-for-mingo-4.13-20170719' of >>> git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core > > Not sure what this is, though. Just mentioned branch and revision when forking local development branch. Considered it helpful for applying the whole patch set. > > As has been recently pointed out elsewhere, you can get a good idea of > how to structure and format commit messages for a particular piece of > code by looking at 'git log path/to/code' and paying attention to common > patterns. > > Thanks, > -- > Alex > Thanks, Alexey
