perf report: Implement perf.data record decompression
zstd_init(, comp_level = 0) initializes decompression part of API only hat now consists of zstd_decompress_stream() function. The perf.data PERF_RECORD_COMPRESSED records are decompressed using zstd_decompress_stream() function into a linked list of mmaped memory regions of mmap_comp_len size (struct decomp). After decompression of one COMPRESSED record its content is iterated and fetched for usual processing. The mmaped memory regions with decompressed events are kept in the linked list till the tool process termination. When dumping raw records (e.g., perf report -D --header) file offsets of events from compressed records are printed as zero. Committer notes: Since now we have support for processing PERF_RECORD_COMPRESSED, we see none, in raw form, like we saw in the previous patch commiter notes, they were decompressed into the usual PERF_RECORD_{FORK,MMAP,COMM,etc} records, we only see the stats for those PERF_RECORD_COMPRESSED events, and since I used the file generated in the commiter notes for the previous patch, there they are, 2 compressed records: $ perf report --header-only | grep cmdline # cmdline : /home/acme/bin/perf record -z2 sleep 1 $ perf report -D | grep COMPRESS COMPRESSED events: 2 COMPRESSED events: 0 $ perf report --stdio # To display the perf.data header info, please use --header/--header-only options. # # # Total Lost Samples: 0 # # Samples: 15 of event 'cycles:u' # Event count (approx.): 962227 # # Overhead Command Shared Object Symbol # ........ ....... ................ ........................... # 46.99% sleep libc-2.28.so [.] _dl_addr 29.24% sleep [unknown] [k] 0xffffffffaea00a67 16.45% sleep libc-2.28.so [.] __GI__IO_un_link.part.1 5.92% sleep ld-2.28.so [.] _dl_setup_hash 1.40% sleep libc-2.28.so [.] __nanosleep 0.00% sleep [unknown] [k] 0xffffffffaea00163 # # (Tip: To see callchains in a more compact form: perf report -g folded) # $ Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com> Reviewed-by: Jiri Olsa <jolsa@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> 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/304b0a59-942c-3fe1-da02-aa749f87108b@linux.intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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