Messages in this thread | | | Subject | Re: [PATCH v8 0/7] perf: Stream comparison | From | "Jin, Yao" <> | Date | Tue, 13 Oct 2020 12:25:09 +0800 |
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Hi Jiri, Hi Arnaldo,
How about v8 series? V6 got ACK from Jiri and I updated the series to v8 according to Arnaldo's comments. Please let me know if there are still some issues for this version then I can continue improving the patchset.
Thanks Jin Yao
On 10/9/2020 10:28 AM, Jin Yao wrote: > Sometimes, a small change in a hot function reducing the cycles of > this function, but the overall workload doesn't get faster. It is > interesting where the cycles are moved to. > > What it would like is to diff before/after streams. The stream is the > branch history which is aggregated by the branch records from perf > samples. For example, the callchains aggregated from the branch records. > By browsing the hot stream, we can understand the hot code path. > > By browsing the hot streams, we can understand the hot code path. > By comparing the cycles variation of same streams between old perf > data and new perf data, we can understand if the cycles are moved > to other codes. > > The before stream is the stream in perf.data.old. The after stream > is the stream in perf.data. > > Diffing before/after streams compares top N hottest streams between > two perf data files. > > If all entries of one stream in perf.data.old are fully matched with > all entries of another stream in perf.data, we think two streams > are matched, otherwise the streams are not matched. > > For example, > > cycles: 1, hits: 26.80% cycles: 1, hits: 27.30% > -------------------------- -------------------------- > main div.c:39 main div.c:39 > main div.c:44 main div.c:44 > > The above streams are matched and we can see for the same streams the > cycles (1) are equal and the callchain hit percents are slightly changed > (26.80% vs. 27.30%). That's expected. > > Now let's see example. > > perf record -b ... Generate perf.data.old with branch data > perf record -b ... Generate perf.data with branch data > perf diff --stream > > [ Matched hot streams ] > > hot chain pair 1: > cycles: 1, hits: 27.77% cycles: 1, hits: 9.24% > --------------------------- -------------------------- > main div.c:39 main div.c:39 > main div.c:44 main div.c:44 > > hot chain pair 2: > cycles: 34, hits: 20.06% cycles: 27, hits: 16.98% > --------------------------- -------------------------- > __random_r random_r.c:360 __random_r random_r.c:360 > __random_r random_r.c:388 __random_r random_r.c:388 > __random_r random_r.c:388 __random_r random_r.c:388 > __random_r random_r.c:380 __random_r random_r.c:380 > __random_r random_r.c:357 __random_r random_r.c:357 > __random random.c:293 __random random.c:293 > __random random.c:293 __random random.c:293 > __random random.c:291 __random random.c:291 > __random random.c:291 __random random.c:291 > __random random.c:291 __random random.c:291 > __random random.c:288 __random random.c:288 > rand rand.c:27 rand rand.c:27 > rand rand.c:26 rand rand.c:26 > rand@plt rand@plt > rand@plt rand@plt > compute_flag div.c:25 compute_flag div.c:25 > compute_flag div.c:22 compute_flag div.c:22 > main div.c:40 main div.c:40 > main div.c:40 main div.c:40 > main div.c:39 main div.c:39 > > hot chain pair 3: > cycles: 9, hits: 4.48% cycles: 6, hits: 4.51% > --------------------------- -------------------------- > __random_r random_r.c:360 __random_r random_r.c:360 > __random_r random_r.c:388 __random_r random_r.c:388 > __random_r random_r.c:388 __random_r random_r.c:388 > __random_r random_r.c:380 __random_r random_r.c:380 > > [ Hot streams in old perf data only ] > > hot chain 1: > cycles: 18, hits: 6.75% > -------------------------- > __random_r random_r.c:360 > __random_r random_r.c:388 > __random_r random_r.c:388 > __random_r random_r.c:380 > __random_r random_r.c:357 > __random random.c:293 > __random random.c:293 > __random random.c:291 > __random random.c:291 > __random random.c:291 > __random random.c:288 > rand rand.c:27 > rand rand.c:26 > rand@plt > rand@plt > compute_flag div.c:25 > compute_flag div.c:22 > main div.c:40 > > hot chain 2: > cycles: 29, hits: 2.78% > -------------------------- > compute_flag div.c:22 > main div.c:40 > main div.c:40 > main div.c:39 > > [ Hot streams in new perf data only ] > > hot chain 1: > cycles: 4, hits: 4.54% > -------------------------- > main div.c:42 > compute_flag div.c:28 > > hot chain 2: > cycles: 5, hits: 3.51% > -------------------------- > main div.c:39 > main div.c:44 > main div.c:42 > compute_flag div.c:28 > > v8: > --- > Rebase to perf/core > > v7: > --- > Create a new struct evlist_streams which contains ev_streams and > nr_evsel, so we don't need to pass nr_evsel in stream related functions. > > Rename functions for better coding style. > > v6: > --- > Rebase to perf/core > > v5: > --- > 1. Remove enum stream_type > 2. Rebase to perf/core > > v4: > --- > The previous version is too big and very hard for review. > > 1. v4 removes the code which supports the source line mapping > table and remove the source line based comparison. Now we > only supports the basic functionality of stream comparison. > > 2. Refactor the code in a generic way. > > v3: > --- > v2 has 14 patches, it's hard to review. > v3 is only 7 patches for basic stream comparison. > > Jin Yao (7): > perf util: Create streams > perf util: Get the evsel_streams by evsel_idx > perf util: Compare two streams > perf util: Link stream pair > perf util: Calculate the sum of total streams hits > perf util: Report hot streams > perf diff: Support hot streams comparison > > tools/perf/Documentation/perf-diff.txt | 4 + > tools/perf/builtin-diff.c | 119 ++++++++- > tools/perf/util/Build | 1 + > tools/perf/util/callchain.c | 99 +++++++ > tools/perf/util/callchain.h | 9 + > tools/perf/util/stream.c | 342 +++++++++++++++++++++++++ > tools/perf/util/stream.h | 41 +++ > 7 files changed, 602 insertions(+), 13 deletions(-) > create mode 100644 tools/perf/util/stream.c > create mode 100644 tools/perf/util/stream.h >
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