changing wrong subject :-\
On Wed, Jan 24, 2018 at 12:51:22PM +0100, Jiri Olsa wrote: > hi, > this RFC contains change to delay sample's user space > data retrieval into task work, originally described and > discussed by Peter and Ingo in here [1]. > > This patchset tries to follow the original patch with > some kernel changes (described below) and perf tool > support included. > > Basically we allow the NMI event code to skip user data > retrieval and schedule task work to do it, before the > task resumes. > > Using the task work limits the window where we can do > this. We can trigger the delayed task work only if the > taskwork gets executed before the process executes again > after NMI, because we need its stack as it was in NMI. > > That leaves us with window during the slow syscall path > (check task_struct::perf_user_data_allowed in patches). > > The slow syscall processing is forced for task when > the user data event is enabled, which makes the task > slower. > > On the other hand I noticed roughly 100us drop in NMI > processing times, which I plotted in here [2]. > > Not sure it's worth to introduce this processing, which adds > more processing time and does not show much improvement. On > the other hand IIRC Peter mentioned it'd be nice to get user > space data retrieval out of NMI. > > Also you guys could think of some other better/faster way ;-) > > NOTE I also implemented putting the user stack data into > delayed processing, which showed nicer numbers. But it's > little more tricky and brings more changes into this already > big patchset. The logic stays, so I did not include it to > keep the patchset simple. > > Also available in: > https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git > perf/user_data > > thanks for comments, > jirka > > [1] https://marc.info/?l=linux-kernel&m=150098372819938&w=2 > [2] http://people.redhat.com/~jolsa/ud-bench.png > > --- > Jiri Olsa (21): > perf tools: Add perf_evsel__is_sample_bit function > perf tools: Add perf_sample__process function > perf tools: Add callchain__printf for pure callchain dump > perf tools: Add perf_sample__copy|free functions > perf: Add TIF_PERF_USER_DATA bit > perf: Add PERF_RECORD_USER_DATA event processing > perf: Add PERF_SAMPLE_USER_DATA_ID sample type > perf: Add PERF_SAMPLE_CALLCHAIN to user data event > perf: Export running sample length values through debugfs > perf tools: Sync perf_event.h uapi header > perf tools: Add perf_sample__parse function > perf tools: Add struct parse_args arg to perf_sample__parse > perf tools: Add support to parse user data event > perf tools: Add support to dump user data event info > perf report: Add delayed user data event processing > perf record: Enable delayed user data events > perf script: Add support to display user data events > perf script: Add support to display user data ID > perf script: Display USER_DATA misc char for sample > perf report: Add user data processing stats > perf report: Add --stats=ud option to display user data debug info > > arch/x86/entry/common.c | 6 +++ > arch/x86/events/core.c | 18 ++++++++ > arch/x86/events/intel/ds.c | 4 +- > arch/x86/include/asm/thread_info.h | 4 +- > include/linux/init_task.h | 4 +- > include/linux/perf_event.h | 3 ++ > include/linux/sched.h | 20 ++++++++ > include/uapi/linux/perf_event.h | 34 +++++++++++++- > kernel/events/core.c | 283 > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-- > tools/include/uapi/linux/perf_event.h | 34 +++++++++++++- > tools/perf/Documentation/perf-script.txt | 3 +- > tools/perf/builtin-record.c | 2 + > tools/perf/builtin-report.c | 301 > +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--------- > tools/perf/builtin-script.c | 98 > +++++++++++++++++++++++++++++++++++++++ > tools/perf/perf.h | 1 + > tools/perf/util/event.c | 1 + > tools/perf/util/event.h | 9 ++++ > tools/perf/util/evsel.c | 118 > +++++++++++++++++++++++++++++++++++++---------- > tools/perf/util/evsel.h | 5 ++ > tools/perf/util/session.c | 60 +++++++++++++++++++----- > tools/perf/util/thread.c | 1 + > tools/perf/util/thread.h | 16 +++++++ > tools/perf/util/tool.h | 1 + > 23 files changed, 954 insertions(+), 72 deletions(-)
