linux-kernel - Re: [PATCH v12 3/3]: perf record: extend trace writing to multi AIO

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Message-ID: <f2e5b55c-5dd8-84e0-dd95-cbb8e17bb888@linux.intel.com>
Date:   Thu, 11 Oct 2018 19:24:16 +0300
From:   Alexey Budankov <alexey.budankov@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        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>
Subject: Re: [PATCH v12 3/3]: perf record: extend trace writing to multi AIO

On 11.10.2018 16:46, Jiri Olsa wrote:
> On Tue, Oct 09, 2018 at 11:59:31AM +0300, Alexey Budankov wrote:
> 
> SNIP
> 
>> @@ -709,12 +729,13 @@ static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evli
>>  					goto out;
>>  				}
>>  			} else {
>> +				int idx;
>>  				/*
>>  				 * Call record__aio_sync() to wait till map->data buffer
>>  				 * becomes available after previous aio write request.
>>  				 */
>> -				record__aio_sync(map);
>> -				if (perf_mmap__aio_push(map, rec, record__aio_pushfn, &off) != 0) {
>> +				idx = record__aio_sync(map, false);
> 
> looks like record__aio_sync can return -1,
> how is it not breaking the perf_mmap__aio_push call below?

Currently -1 may be returned only when calling with 
sync_all==true i.e. record__aio_sync(, true).

Thanks,
Alexey

> 
>> +				if (perf_mmap__aio_push(map, rec, idx, record__aio_pushfn, &off) != 0) {
>>  					record__aio_set_pos(trace_fd, off);
>>  					rc = -1;
>>  					goto out;
> 
> SNIP
>