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Compression is implemented using the functions from zstd.c. As the memory to operate on the compression uses mmap->aio.data[] buffers. If Zstd streaming compression API fails for some reason the data to be compressed are just copied into the memory buffers using plain memcpy(). Compressed trace frame consists of an array of PERF_RECORD_COMPRESSED records. Each element of the array is not longer that PERF_SAMPLE_MAX_SIZE and consists of perf_event_header followed by the compressed chunk that is decompressed on the loading stage. perf_mmap__aio_push() is replaced by perf_mmap__push() which is now used in the both serial and AIO streaming cases. perf_mmap__push() is extended with positive return values to signify absence of data ready for processing. Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com> Reviewed-by: Jiri Olsa <jolsa@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/77db2b2c-5d03-dbb0-aeac-c4dd92129ab9@linux.intel.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.