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SubjectRe: [PATCH v12 2/3]: perf record: enable asynchronous trace writing
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On 11.10.2018 17:15, Jiri Olsa wrote:
> On Tue, Oct 09, 2018 at 11:58:53AM +0300, Alexey Budankov wrote:
>>
>> Trace file offset is read once before mmaps iterating loop and written
>> back after all performance data enqueued for aio writing. Trace file offset
>> is incremented linearly after every successful aio write operation.
>>
>> record__aio_sync() blocks till completion of started AIO operation
>> and then proceeds.
>>
>> record__mmap_read_sync() implements a barrier for all incomplete
>> aio write requests.
>>
>> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
>> ---
>> Changes in v12:
>> - implemented record__aio_get/set_pos(), record__aio_enabled()
>> - implemented simple --aio option
>> Changes in v11:
>> - replacing the both lseek() syscalls in every loop iteration by the only
>> two syscalls just before and after the loop at record__mmap_read_evlist()
>> and advancing *in-flight* off file pos value at perf_mmap__aio_push()
>> Changes in v10:
>> - avoided lseek() setting file pos back in case of record__aio_write() failure
>> - compacted code selecting between serial and AIO streaming
>> - optimized call places of record__mmap_read_sync()
>> Changes in v9:
>> - enable AIO streaming only when --aio-cblocks option is specified explicitly
>> Changes in v8:
>> - split AIO completion check into separate record__aio_complete()
>> Changes in v6:
>> - handled errno == EAGAIN case from aio_write();
>> Changes in v5:
>> - data loss metrics decreased from 25% to 2x in trialed configuration;
>> - avoided nanosleep() prior calling aio_suspend();
>> - switched to per cpu multi record__aio_sync() aio
>> - record_mmap_read_sync() now does global barrier just before
>> switching trace file or collection stop;
>> - resolved livelock on perf record -e intel_pt// -- dd if=/dev/zero of=/dev/null count=100000
>> Changes in v4:
>> - converted void *bf to struct perf_mmap *md in signatures
>> - written comment in perf_mmap__push() just before perf_mmap__get();
>> - written comment in record__mmap_read_sync() on possible restarting
>> of aio_write() operation and releasing perf_mmap object after all;
>> - added perf_mmap__put() for the cases of failed aio_write();
>> Changes in v3:
>> - written comments about nanosleep(0.5ms) call prior aio_suspend()
>> to cope with intrusiveness of its implementation in glibc;
>> - written comments about rationale behind coping profiling data
>> into mmap->data buffer;
>> ---
>> tools/perf/Documentation/perf-record.txt | 5 +
>> tools/perf/builtin-record.c | 220 ++++++++++++++++++++++++++++++-
>> tools/perf/perf.h | 1 +
>> tools/perf/util/evlist.c | 6 +-
>> tools/perf/util/evlist.h | 2 +-
>> tools/perf/util/mmap.c | 86 +++++++++++-
>> tools/perf/util/mmap.h | 5 +
>> 7 files changed, 316 insertions(+), 9 deletions(-)
>>
>> diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
>> index 246dee081efd..5cedb3e75434 100644
>> --- a/tools/perf/Documentation/perf-record.txt
>> +++ b/tools/perf/Documentation/perf-record.txt
>> @@ -435,6 +435,11 @@ 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.
>
> nit, there's an extra whitespace at the end of above line,
> making the 'git am' to not apply your patch

Corrected trailing whitespace. Thanks!

- Alexey

>
> thanks,
> jirka
>

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