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SubjectRe: [PATCH v4 0/10] perf: enable compression of record mode trace to save storage space
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On 13.03.2019 17:37, Jiri Olsa wrote:
> On Thu, Feb 28, 2019 at 11:35:24AM +0300, Alexey Budankov wrote:
>>
>> The patch set implements runtime trace compression (-z option) in
>> record mode and trace auto decompression in report and inject modes.
>> Streaming Zstandard (Zstd) API (zstd) is used for compression and
>> decompression of data that come from kernel mmaped data buffers.
>>
>> Usage of implemented -z,--compression_level=n option provides ~3-5x
>> avg. trace file size reduction on variety of tested workloads what
>> saves storage space on larger server systems where trace file size
>> can easily reach several tens or even hundreds of GiBs, especially
>> when profiling with dwarf-based stacks and tracing of context switches.
>> Implemented -f,--mmap-flush option can be used to avoid compressing
>> every single byte of data and increase compression ratio at the same
>> time lowering tool runtime overhead. Default option value is 1 what
>> is equal to the current perf record implementation. The option is
>> independent from -z setting and doesn't vary with compression level:
>>
>> $ tools/perf/perf record -z 1 -e cycles -- matrix.gcc
>> $ tools/perf/perf record --aio=1 -z 1 -e cycles -- matrix.gcc
>> $ tools/perf/perf record -z 1 -f 1024 -e cycles -- matrix.gcc
>> $ tools/perf/perf record --aio=1 -z 1 -f 1024 -e cycles -- matrix.gcc
>
> please make the 'z' option to choose some default value,
> so it's possible just to run:
>
> perf record -z ...
>
> to get comrpessed data.. not sure which strategy to use,
> probably the fastest '-z 1' as default
>
> with some warning about using that default value perhaps

in v8.

~Alexey

>
> jirka
>

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