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If virtual timestamps are detected, set sample time field accordingly, otherwise warn the user that the samples will not include accurate time data. | Test notes (FEAT_TRF platform) | | $ ./perf record -e cs_etm//u -a -- sleep 4 | $ ./perf script --fields +time | perf 422 [000] 163.375100: 1 branches:uH: 0 [unknown] ([unknown]) | perf 422 [000] 163.375100: 1 branches:uH: ffffb8009544 ioctl+0x14 (/lib/aarch64-linux-gnu/libc-2.27.so) | perf 422 [000] 163.375100: 1 branches:uH: aaaaab6bebf4 perf_evsel__run_ioctl+0x90 (/home/german/linux/tools/perf/perf) | [...] | perf 422 [000] 167.393100: 1 branches:uH: aaaaab6bda00 __xyarray__entry+0x74 (/home/german/linux/tools/perf/perf) | perf 422 [000] 167.393099: 1 branches:uH: aaaaab6bda0c __xyarray__entry+0x80 (/home/german/linux/tools/perf/perf) | perf 422 [000] 167.393099: 1 branches:uH: ffffb8009538 ioctl+0x8 (/lib/aarch64-linux-gnu/libc-2.27.so) | | The time from the first sample to the last sample is 4 seconds Now that times are converted to nanoseconds, also try to estimate the timestamps more accurately be dividing by some fixed value for instructions per ns. This prevents long ranges from being estimated too far in the past than would be realistic. Signed-off-by: German Gomez <german.gomez@arm.com> Acked-by: Suzuki Poulouse <suzuki.poulose@arm.com> Tested-by: Tanmay Jagdale <tanmay@marvell.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Bharat Bhushan <bbhushan2@marvell.com> Cc: George Cherian <gcherian@marvell.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: John Garry <john.g.garry@oracle.com> Cc: Leo Yan <leo.yan@linaro.org> Cc: Linu Cherian <lcherian@marvell.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: Mike Leach <mike.leach@linaro.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sunil Kovvuri Goutham <sgoutham@marvell.com> Cc: Will Deacon <will@kernel.org> Cc: coresight@lists.linaro.org Cc: linux-arm-kernel@lists.infradead.org Link: https://lore.kernel.org/r/20230120143702.4035046-8-james.clark@arm.com Signed-off-by: James Clark <james.clark@arm.com> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.