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Message-ID: <60253e6d-e8c5-550e-73b5-40720114c2a4@linux.intel.com>
Date:   Mon, 21 Feb 2022 16:24:28 +0300
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Subject: Re: [PATCH core] perf data: Adding error message if
 perf_data__create_dir fails
Content-Language: en-GB
To:     Jiri Olsa <olsajiri@gmail.com>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Andi Kleen <ak@linux.intel.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Alexander Antonov <alexander.antonov@linux.intel.com>,
        Alexei Budankov <abudankov@huawei.com>
References: <20220218152341.5197-1-alexey.v.bayduraev@linux.intel.com>
 <YhLEHCttvXmRu78G@krava>
From:   "Bayduraev, Alexey V" <alexey.v.bayduraev@linux.intel.com>
Organization: Intel Corporation
In-Reply-To: <YhLEHCttvXmRu78G@krava>
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On 21.02.2022 1:43, Jiri Olsa wrote:
> On Fri, Feb 18, 2022 at 06:23:40PM +0300, Alexey Bayduraev wrote:
>> There is no notification about data directory creation failure. Add it.
>>
>> Signed-off-by: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
>> ---
>>  tools/perf/builtin-record.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>> index 0bc6529814b2..0306d5911de2 100644
>> --- a/tools/perf/builtin-record.c
>> +++ b/tools/perf/builtin-record.c
>> @@ -1186,8 +1186,10 @@ static int record__mmap_evlist(struct record *rec,
>>  
>>  	if (record__threads_enabled(rec)) {
>>  		ret = perf_data__create_dir(&rec->data, evlist->core.nr_mmaps);
>> -		if (ret)
>> +		if (ret) {
>> +			pr_err("Failed to create data directory: %s\n", strerror(errno));
> 
> errno will be misleading in here, because perf_data__create_dir
> calls other syscalls on error path

Mostly I want to output something like:

  Failed to create data dir: Too many open files

This will trigger the user to increase the open files limit.
Would it be better to place such message to perf_data__create_dir after 
open() syscall?

Regards,
Alexey

> 
> jirka
> 
>>  			return ret;
>> +		}
>>  		for (i = 0; i < evlist->core.nr_mmaps; i++) {
>>  			if (evlist->mmap)
>>  				evlist->mmap[i].file = &rec->data.dir.files[i];
>> -- 
>> 2.19.0
>>