Messages in this thread | | | Date | Mon, 27 Aug 2018 10:38:52 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH v2 2/2]: perf record: enable asynchronous trace writing |
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On Thu, Aug 23, 2018 at 07:47:01PM +0300, Alexey Budankov wrote:
SNIP
> static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evlist, > bool overwrite) > { > u64 bytes_written = rec->bytes_written; > - int i; > - int rc = 0; > + int i, rc = 0; > struct perf_mmap *maps; > + int trace_fd = rec->session->data->file.fd; > + struct aiocb **mmap_aio = rec->evlist->mmap_aio; > + int mmap_aio_size = 0; > + off_t off; > > if (!evlist) > return 0; > @@ -546,14 +620,17 @@ 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; > > + off = lseek(trace_fd, 0, SEEK_CUR); > +
with async write, do we need to query/set the offset like this all the time?
could we just keep/update the offset value in the 'struct perf_data_file' and skip both lseek calls?
jirka
SNIP
> > + record__mmap_read_sync(trace_fd, mmap_aio, mmap_aio_size, rec); > + > + lseek(trace_fd, off, SEEK_SET); > +
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