linux-kernel - Re: [PATCH v2 1/2]: perf util: map data buffer for preserving collected data

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Date:   Mon, 27 Aug 2018 11:58:56 +0300
From:   Alexey Budankov <alexey.budankov@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v2 1/2]: perf util: map data buffer for preserving
 collected data

Hi Jiri,

On 27.08.2018 11:28, Jiri Olsa wrote:
> On Thu, Aug 23, 2018 at 07:42:09PM +0300, Alexey Budankov wrote:
>>
>> The data buffer and accompanying AIO control block are allocated at 
>> perf_mmap object and the mapped data buffer size is equal to 
>> the kernel one.
>>
>> The buffer is then used to preserve profiling data ready for dumping 
>> and queue it for asynchronous writing into perf trace thru implemented 
>> record__aio_write() function.
>>
>> mmap_aio control structure of the size equal to the number of per-cpu 
>> kernel buffers is used to keep pointers to enqueued AIO control 
>> blocks for monitoring of completed AIO operations.
>>
>> Signed-off-by: Alexey Budankov <alexey.budankov@...ux.intel.com>
>> ---
>> Changes in v2:
>> - converted zalloc() to calloc() for allocation of mmap_aio array,
>> - cleared typo and adjusted fallback branch code;
>> ---
>> tools/perf/builtin-record.c | 18 ++++++++++++++++++
>>  tools/perf/util/evlist.c    |  7 +++++++
>>  tools/perf/util/evlist.h    |  2 ++
>>  tools/perf/util/mmap.c      | 12 ++++++++++++
>>  tools/perf/util/mmap.h      |  3 +++
>>  5 files changed, 42 insertions(+)
>>
>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>> index 22ebeb92ac51..a35675e9f3aa 100644
>> --- a/tools/perf/builtin-record.c
>> +++ b/tools/perf/builtin-record.c
>> @@ -53,6 +53,7 @@
>>  #include <sys/mman.h>
>>  #include <sys/wait.h>
>>  #include <linux/time64.h>
>> +#include <aio.h>
>>  
>>  struct switch_output {
>>  	bool		 enabled;
>> @@ -121,6 +122,23 @@ static int record__write(struct record *rec, void *bf, size_t size)
>>  	return 0;
>>  }
>>  
>> +static int record__aio_write(int trace_fd, struct aiocb *cblock,
>> +		void *buf, size_t size, off_t off)
>> +{
> 
> this breaks bisection:
> 
> builtin-record.c:125:12: error: ‘record__aio_write’ defined but not used [-Werror=unused-function]
>  static int record__aio_write(int trace_fd, struct aiocb *cblock,

Moving it to [PATCH v3 2/2]. Thanks!

> 
> jirka
>