Re: [PATCH v2 2/4] perf record: implement -z=<level> and --mmap-flush=<thres> options

From: Alexey Budankov
Date: Wed Feb 20 2019 - 09:14:45 EST



On 12.02.2019 16:09, Jiri Olsa wrote:
> On Mon, Feb 11, 2019 at 11:22:38PM +0300, Alexey Budankov wrote:
>
> SNIP
>
>> @@ -1147,6 +1193,10 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>> fd = perf_data__fd(data);
>> rec->session = session;
>>
>> + rec->opts.comp_level = 0;
>> + session->header.env.comp_level = rec->opts.comp_level;
>> + session->header.env.comp_type = PERF_COMP_NONE;
>> +
>> record__init_features(rec);
>>
>> if (rec->opts.use_clockid && rec->opts.clockid_res_ns)
>> @@ -1176,6 +1226,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>> err = -1;
>> goto out_child;
>> }
>> + session->header.env.comp_mmap_len = session->evlist->mmap_len;
>
> so the comp_mmap_len is the max length of the compressed packet?

comp_mmap_len is the size of buffer to encompass one compressed chunk
of data after its decompression.

>
> any idea if this value might have some impact on the processing speed?

It increases memory consumption at the loading and processing stages.

>
> I see you mentioned the size reduction, could you also meassure
> the record overhead?

Let's get back to this after the code review.

Thanks,
Alexey

>
> thanks,
> jirka
>