Messages in this thread | | | From | Namhyung Kim <> | Date | Fri, 27 Jan 2023 15:08:37 -0800 | Subject | Re: [PATCH 0/4] perf intel-pt: Fix the pipe mode (v1) |
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Hi James,
On Fri, Jan 27, 2023 at 6:42 AM James Clark <james.clark@arm.com> wrote: > > > > On 27/01/2023 07:22, Adrian Hunter wrote: > > On 27/01/23 02:19, Namhyung Kim wrote: > >> Hello, > >> > >> I found some problems in Intel-PT and auxtrace in general with pipe. > >> In the past it used to work with pipe, but recent code fails. > > > > Pipe mode is a problem for Intel PT and possibly other auxtrace users. > > Just some info from my side: For Arm Coresight we ended up deprecating > pipe mode, then not supporting it altogether. First was when we added an > optional step to peek through all of the data to help with an edge case. > Then we added a requirement to receive a HW_ID packet before decoding > which necessitated the peek. You can't peek in pipe mode because you > need to be able to seek, so it's not supported at all anymore. > > For Arm SPE I never tested it with piped data. I suppose I could add a > test at some point, but I don't really see the usecase.
Yeah, it'd be great if we can have a test for Arm SPE.
Anyway, my work env (Google) requires the pipe mode due to the restriction in disk usage. Without the pipe support, it's not possible to run `perf record` in production.
Thanks, Namhyung
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