d1efa4a0a6
Timeless and per-thread are orthogonal concepts that are currently treated as if they are the same (per-thread == timeless). This breaks when you modify the command line or itrace options to something that the current logic doesn't expect. For example: # Force timeless with Z --itrace=Zi10i # Or inconsistent record options -e cs_etm/timestamp=1/ --per-thread Adding Z for decoding in per-cpu mode is particularly bad because in per-thread mode trace channel IDs are discarded and all assumed to be 0, which would mix trace from different CPUs in per-cpu mode. Although the results might not be perfect in all scenarios, if the user requests no timestamps, it should still be possible to decode in either mode. Especially if the relative times of samples in different processes aren't interesting, quite a bit of space can be saved by turning off timestamps in per-cpu mode. Signed-off-by: James Clark <james.clark@arm.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Denis Nikitin <denik@google.com> Cc: Ian Rogers <irogers@google.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: 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: Suzuki Poulouse <suzuki.poulose@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Yang Shi <shy828301@gmail.com> Cc: coresight@lists.linaro.org Cc: linux-arm-kernel@lists.infradead.org Link: https://lore.kernel.org/r/20230424134748.228137-8-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.