summaryrefslogtreecommitdiff
path: root/tools/perf/Documentation
diff options
context:
space:
mode:
authorAlexey Budankov <alexey.budankov@linux.intel.com>2018-11-06 12:07:19 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2018-12-17 20:55:11 +0300
commit93f20c0fe3e86088ec041e47755367c4bed584c6 (patch)
tree108d59a511a822fa122db8371b2b49e243b885e9 /tools/perf/Documentation
parentd3d1af6f011a553a00d2bda90b2700c0d56bd8f7 (diff)
downloadlinux-93f20c0fe3e86088ec041e47755367c4bed584c6.tar.xz
perf record: Extend trace writing to multi AIO
Multi AIO trace writing allows caching more kernel data into userspace memory postponing trace writing for the sake of overall profiling data thruput increase. It could be seen as kernel data buffer extension into userspace memory. With an --aio option value different from 0 (default value is 1) the tool has capability to cache more and more data into user space along with delegating spill to AIO. That allows avoiding to suspend at record__aio_sync() between calls of record__mmap_read_evlist() and increases profiling data thruput at the cost of userspace memory. Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com> Reviewed-by: Jiri Olsa <jolsa@redhat.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/050bb053-e7f3-aa83-fde7-f27ff90be7f6@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/Documentation')
-rw-r--r--tools/perf/Documentation/perf-record.txt4
1 files changed, 2 insertions, 2 deletions
diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 7efb4af88a68..d232b13ea713 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -435,8 +435,8 @@ Specify vmlinux path which has debuginfo.
--buildid-all::
Record build-id of all DSOs regardless whether it's actually hit or not.
---aio::
-Enable asynchronous (Posix AIO) trace writing mode.
+--aio[=n]::
+Use <n> control blocks in asynchronous (Posix AIO) trace writing mode (default: 1, max: 4).
Asynchronous mode is supported only when linking Perf tool with libc library
providing implementation for Posix AIO API.