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

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Date:   Mon, 25 Feb 2019 18:27:27 +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 20.02.2019 18:09, Alexey Budankov wrote:
> 
> 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.

Redesigned compress() to be the param for __push() __aio_push() so this 
__comp_enabled() if could be avoided. Overloading of __pushfn() doesn't 
fit for aio case.

> 
> Thanks,
> Alexey
> 
>>
>> thanks,
>> jirka
>>
>