linux-kernel - Re: [PATCH v2 3/4] perf record: enable runtime trace compression

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Message-ID: <d225cd8c-3447-331a-78ac-070c5b9a442d@linux.intel.com>
Date:   Wed, 20 Feb 2019 18:09:36 +0300
From:   Alexey Budankov <alexey.budankov@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/4] perf record: enable runtime trace compression


On 12.02.2019 16:09, Jiri Olsa wrote:
> On Mon, Feb 11, 2019 at 11:23:40PM +0300, Alexey Budankov wrote:
> 
> SNIP
> 
>> +	compress_fn = (record__comp_enabled(rec) ?
>> +		perf_session__zstd_compress : perf_session__zstd_copy);
>> +
>>  	if (record__aio_enabled(rec))
>>  		off = record__aio_get_pos(trace_fd);
>>  
>> @@ -799,11 +805,21 @@ static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evli
>>  				map->flush = MMAP_FLUSH_DEFAULT;
>>  			}
>>  			if (!record__aio_enabled(rec)) {
>> -				if (perf_mmap__push(map, rec, record__pushfn) != 0) {
>> -					if (sync)
>> -						map->flush = flush;
>> -					rc = -1;
>> -					goto out;
>> +				if (!record__comp_enabled(rec)) {
>> +					if (perf_mmap__push(map, rec, record__pushfn) != 0) {
>> +						if (sync)
>> +							map->flush = flush;
>> +						rc = -1;
>> +						goto out;
>> +					}
>> +				} else {
>> +					if (perf_mmap__pack(map, rec, record__pushfn,
>> +							compress_fn, session) != 0) {
>> +						if (sync)
>> +							map->flush = flush;
>> +						rc = -1;
>> +						goto out;
>> +					}
> 
> I really dont like this.. the non-compression flow needs to stay untouched
> 
> why don't you overload the record__pushfn function for compression
> processing and stash the data in there?

Yes, this becomes complicated and overloading could be an option to simplify it.

Thanks,
Alexey

> 
> thanks,
> jirka
>