Hi Al, On Tue, Apr 06, 2021 at 09:38:32AM +0000, Al Grant wrote:
[...] > > This patch set is to enable timestamp for Arm SPE trace. It reads out TSC > > parameters from mmap page and stores into auxtrace info structure; > > Why not synthesize a PERF_RECORD_TIME_CONV - isn't that specifically to > capture the TSC parameters from the mmap page? If a generic mechanism > exists it would be better to use it, otherwise we'll have to do this again for > future trace formats. Good point! Actually "perf record" tool has synthesized event PERF_RECORD_TIME_CONV. This patch series is studying the implementation from Intel-PT, so the question is why the existed implementations (like Intel-PT, Intel-BTS) don't directly use PERF_RECORD_TIME_CONV for retriving TSC parameters. I agree using PERF_RECORD_TIME_CONV for TSC parameter is better than extending auxtrace info. Will experiment for this. > perf_read_tsc_conversion and perf_event__synth_time_conv are currently > in arch/x86/util/tsc.c, but nothing in them is x86-specific and they could be > moved somewhere more generic. This is not true on the mainline kernel; these functions have been moved into the file util/tsc.c. Thanks for suggestions, Leo
