On 7/04/21 4:15 pm, Leo Yan wrote: > 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.
PERF_RECORD_TIME_CONV was added later because the TSC information is needed by jitdump.