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

[Alexey Budankov <alexey.budankov@linux.intel.com>]

On 21.02.2019 12:43, Jiri Olsa wrote:
> On Wed, Feb 20, 2019 at 05:53:17PM +0300, Alexey Budankov wrote:
>>
>> On 12.02.2019 16:08, Jiri Olsa wrote:
>>> On Mon, Feb 11, 2019 at 11:23:40PM +0300, Alexey Budankov wrote:
>>>
>>> SNIP
>>>
>>>> @@ -774,6 +775,8 @@ static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evli
>>>>  	struct perf_mmap *maps;
>>>>  	int trace_fd = rec->data.file.fd;
>>>>  	off_t off;
>>>> +	struct perf_session *session = rec->session;
>>>> +	perf_mmap__compress_fn_t compress_fn;
>>>>  
>>>>  	if (!evlist)
>>>>  		return 0;
>>>> @@ -785,6 +788,9 @@ static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evli
>>>>  	if (overwrite && evlist->bkw_mmap_state != BKW_MMAP_DATA_PENDING)
>>>>  		return 0;
>>>>  
>>>> +	compress_fn = (record__comp_enabled(rec) ?
>>>> +		perf_session__zstd_compress : perf_session__zstd_copy);
>>>> +
>>>
>>> I don't follow what's the perf_session__zstd_copy function for..?
>>
>> It bridges AIO without compression case.
> 
> so current state then.. why do we need new function for that?

This copy() function has the same signature as compress() 
so it can be used as the replacement in the _pack() call 
instead of memcpy() with different signature.

Thanks,
Alexey

> 
> jirka