Messages in this thread | | | Date | Fri, 15 Mar 2019 13:28:11 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH v8 00/12] perf: enable compression of record mode trace to save storage space |
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On Thu, Mar 14, 2019 at 02:26:23PM +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 Zstd API [1] 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. > Default option value is 1 (fastest compression). > > Implemented --mmap-flush option can be used to specify minimal size > of data chunk that is extracted from mmaped kernel buffer to store > into a trace. The option is independent from -z setting and doesn't > vary with compression level. The default option value is 1 byte what > means every time trace writing thread finds some new data in the > mmaped buffer the data is extracted, possibly compressed and written > to a trace. The option serves two purposes the first one is to increase > the compression ratio of trace data and the second one is to avoid > live-lock self tool process monitoring in system wide (-a) profiling > mode. Profiling in system wide mode with compression (-a -z) can > additionally induce data into the kernel buffers along with the data > from monitored processes. If performance data rate and volume from > the monitored processes is high then trace streaming and compression > activity in the tool is also high. It can lead to subtle live-lock > effect of endless activity when compression of single new byte from > some of mmaped kernel buffer induces the next single byte at some > mmaped buffer. So perf tool thread never stops on polling event file > descriptors. Varying data chunk size to be extracted from mmap buffers > allows avoiding live-locking self monitoring in system wide mode and > makes mmap buffers polling loop configurable. > > $ tools/perf/perf record -z -e cycles -- matrix.gcc > $ tools/perf/perf record --aio -z -e cycles -- matrix.gcc > $ tools/perf/perf record -z --mmap-flush 1024 -e cycles -- matrix.gcc > $ tools/perf/perf record --aio -z --mmap-flush 1K -e cycles -- matrix.gcc
hi, I'm getting error with -z:
[root@krava perf]# ./perf record -z ./perf bench sched messaging -l 10000 # Running 'sched/messaging' benchmark: # 20 sender and receiver processes per group # 10 groups == 400 processes run
Total time: 18.775 [sec] [ perf record: Woken up 57 times to write data ] 0x5228 [0]: failed to process type: 81 [ perf record: Captured and wrote 6.453 MB perf.data, compressed (original 21.486 MB, ratio is 3.340) ]
jirka
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