Messages in this thread | | | Date | Tue, 28 Aug 2018 14:21:16 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH v3 2/2]: perf record: enable asynchronous trace writing |
| |
On Tue, Aug 28, 2018 at 02:31:04PM +0300, Alexey Budankov wrote: > Hi, > > On 28.08.2018 11:57, Jiri Olsa wrote: > > On Mon, Aug 27, 2018 at 09:16:55PM +0300, Alexey Budankov wrote: > > > > SNIP > > > >> + 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; > >> @@ -528,14 +632,17 @@ 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); > >> + > >> for (i = 0; i < evlist->nr_mmaps; i++) { > >> struct auxtrace_mmap *mm = &maps[i].auxtrace_mmap; > >> > >> if (maps[i].base) { > >> - if (perf_mmap__push(&maps[i], rec, record__pushfn) != 0) { > >> - rc = -1; > >> + rc = perf_mmap__push(&maps[i], rec, record__pushfn, &off); > >> + if (rc < 0) > >> goto out; > >> - } > >> + else if (rc > 0) > >> + mmap_aio[mmap_aio_size++] = &maps[i].cblock; > > > > I understand the purpose of mmap_aio array, but I don't see a reason > > to fill it in every time we call record__mmap_read_evlist > > The cycle trips the same number of iterations over kernel buffers > for every call of record__mmap_read_evlist(). Called perf_mmap__push() > checks if there is data ready for spill in the corresponding buffer > and if there is no such data returns 0. So every time we execute > the cycle we get different set of buffers to spill and in this > circumstances dynamic filling of mmap_aio looks preferable. > Lifetime management of perf_mmap object and referenced memory > is not related another thing.
argh.. the perf_mmap__push returns 0 for empty buffer, ok
jirka
| |