On Fri, Jul 10, 2020 at 06:11:04PM +0300, Adrian Hunter wrote: > A single q option decodes ip from only FUP/TIP packets. Make it so that > repeating the q option (i.e. qq) decodes only PSB+, getting ip if there is > a FUP packet within PSB+ (i.e. between PSB and PSBEND). > > Example: > > $ perf record -e intel_pt//u grep -rI pudding drivers > [ perf record: Woken up 52 times to write data ] > [ perf record: Captured and wrote 57.870 MB perf.data ] > $ time perf script --itrace=bi | wc -l > 58948289 > > real 1m23.863s > user 1m23.251s > sys 0m7.452s > $ time perf script --itrace=biq | wc -l > 3385694 > > real 0m4.453s > user 0m4.455s > sys 0m0.328s > $ time perf script --itrace=biqq | wc -l > 1883 > > real 0m0.047s > user 0m0.043s > sys 0m0.009s > > Signed-off-by: Adrian Hunter <[email protected]> > --- > tools/perf/Documentation/perf-intel-pt.txt | 15 +++++++++++++++ > .../util/intel-pt-decoder/intel-pt-decoder.c | 18 ++++++++++++++++++ > 2 files changed, 33 insertions(+) > > diff --git a/tools/perf/Documentation/perf-intel-pt.txt > b/tools/perf/Documentation/perf-intel-pt.txt > index f9fe4a4040ba..d5a266d7f15b 100644 > --- a/tools/perf/Documentation/perf-intel-pt.txt > +++ b/tools/perf/Documentation/perf-intel-pt.txt > @@ -999,6 +999,21 @@ What *will* be decoded with the (single) q option: > Note the q option does not specify what events will be synthesized e.g. the p > option must be used also to show power events. > > +Repeating the q option (double-q i.e. qq) results in even faster decoding > and even > +less detail. The decoder decodes only extended PSB (PSB+) packets, getting > the > +instruction pointer if there is a FUP packet within PSB+ (i.e. between PSB > and > +PSBEND). Note PSB packets occur regularly in the trace based on the > psb_period > +config term (refer config terms section). There will be a FUP packet if the > +PSB+ occurs while control flow is being traced.
Some estimate would be good how frequent that is. If we assume one bit per instruction then a 2K period it's roughly 16k instructions, with the 16K period roughly 128K instructions. Could be added in a followon patch. But looks overall the patches look good to me now. (for the whole series) Reviewed-by: Andi Kleen <[email protected]>
