Re: [PATCH v11 2/3]: perf record: enable asynchronous trace writing

Alexey Budankov
2018-10-08T12:15:28Z

Hi,

On 08.10.2018 13:57, Jiri Olsa wrote:
> On Mon, Oct 08, 2018 at 09:17:11AM +0300, Alexey Budankov wrote:
>
> SNIP
>
>> static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evlist,
>> bool overwrite)
>> {
>> @@ -520,7 +644,10 @@ static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evli
>> int i;
>> int rc = 0;
>> struct perf_mmap *maps;
>> -
>> +#ifdef HAVE_AIO_SUPPORT
>> + int trace_fd = rec->data.file.fd;
>> + off_t off;
>> +#endif
>> if (!evlist)
>> return 0;
>>
>> @@ -531,14 +658,34 @@ 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;
>>
>> +#ifdef HAVE_AIO_SUPPORT
>> + off = lseek(trace_fd, 0, SEEK_CUR);
>> +#endif
>> for (i = 0; i < evlist->nr_mmaps; i++) {
>> struct perf_mmap *map = &maps[i];
>>
>> if (map->base) {
>> - if (perf_mmap__push(map, rec, record__pushfn) != 0) {
>> - rc = -1;
>> - goto out;
>> +#ifdef HAVE_AIO_SUPPORT
>> + if (!rec->opts.nr_cblocks) {
>> +#endif
>> + if (perf_mmap__push(map, rec, record__pushfn) != 0) {
>> + rc = -1;
>> + goto out;
>> + }
>> +#ifdef HAVE_AIO_SUPPORT
>> + } else {
>> + /*
>> + * Call record__aio_sync() to wait till map->data buffer
>> + * becomes available after previous aio write request.
>> + */
>> + record__aio_sync(map);
>> + if (perf_mmap__aio_push(map, rec, record__aio_pushfn, &off) != 0) {
>> + lseek(trace_fd, off, SEEK_SET);
>> + rc = -1;
>> + goto out;
>> + }
>> }
>> +#endif
>
> I really don't like this.. let's have some aio_... function with its
> dummy counterpart to be called in here.. and again.. if we realyl must
> have this compiled optionaly, which I'm not convinced of

Accepted.

Thanks,
Alexey

>
> jirka
>