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

Jiri Olsa
2018-10-08T12:53:15Z

On Mon, Oct 08, 2018 at 03:24:31PM +0300, Alexey Budankov wrote:
> Hi,
>
> On 08.10.2018 13:52, Jiri Olsa wrote:
> > On Mon, Oct 08, 2018 at 09:17:11AM +0300, Alexey Budankov wrote:
> <SNIP>
> >> +#ifdef HAVE_AIO_SUPPORT
> >> + off = lseek(trace_fd, 0, SEEK_CUR);
> >> +#endif
> >
> > I'm still little puzzled why we need to do this,
> > when the aio write takes the offset value, but
>
> pwrite() syscall [1] which is the base for aio_write() doesn't
> advance file pos value so it requires to be calculated and
> updated by callers of aio_write() API.

ok, so aio_write does not need the offset to be updated,
who needs it then?

jirka