| Message ID | 20190124203801.18484-3-cus@passwd.hu |
|---|---|
| State | Withdrawn |
| Headers | show |
2019-01-24 21:38 GMT+01:00, Marton Balint <cus@passwd.hu>: > Strangely the previous commit caused a slowdown in overall performance > and this fixes it. I used gcc 7.3.1. Does anybody else see this? No, but since this command exists nearly immediately for me I see a 5% deviation even without your patch. Carl Eugen
On Fri, 25 Jan 2019, Carl Eugen Hoyos wrote: > 2019-01-24 21:38 GMT+01:00, Marton Balint <cus@passwd.hu>: >> Strangely the previous commit caused a slowdown in overall performance >> and this fixes it. I used gcc 7.3.1. Does anybody else see this? > > No, but since this command exists nearly immediately for me > I see a 5% deviation even without your patch. Thanks for checking it. I tested my series on top of 1b126ec4087ab5d87d413116bee666495b0d2d3e, and can still reproduce the speedup on it. On the other hand, on current git head, I can no longer reproduce the speedup. Whatever this is, the fact that using av_unlikely fixed it is probably just luck. So considering the mixed feelings about av_(un)likely in general, I'll just drop patch 1 and 3. Thanks, Marton
2019-01-25 2:03 GMT+01:00, Marton Balint <cus@passwd.hu>: > > On Fri, 25 Jan 2019, Carl Eugen Hoyos wrote: > >> 2019-01-24 21:38 GMT+01:00, Marton Balint <cus@passwd.hu>: >>> Strangely the previous commit caused a slowdown in overall performance >>> and this fixes it. I used gcc 7.3.1. Does anybody else see this? >> >> No, but since this command exists nearly immediately for me >> I see a 5% deviation even without your patch. > > Thanks for checking it. I tested my series on top of > 1b126ec4087ab5d87d413116bee666495b0d2d3e, and can still reproduce the > speedup on it. On the other hand, on current git head, I can no longer > reproduce the speedup. Whatever this is, the fact that using av_unlikely > fixed it is probably just luck. > > So considering the mixed feelings about av_(un)likely in general, I'll > just drop patch 1 and 3. I would love to test a command line where it makes a (very) clear difference, I wonder a little about the claim that it would help (measurably) on some systems but not others. Carl Eugen
diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c index b04fd7b4f4..3003739b38 100644 --- a/libavformat/mpegts.c +++ b/libavformat/mpegts.c @@ -2477,7 +2477,7 @@ static int handle_packet(MpegTSContext *ts, const uint8_t *packet) pid = AV_RB16(packet + 1) & 0x1fff; is_start = packet[1] & 0x40; tss = ts->pids[pid]; - if (ts->auto_guess && !tss && is_start) { + if (av_unlikely(ts->auto_guess && !tss && is_start)) { add_pes_stream(ts, pid, -1); tss = ts->pids[pid]; }
Strangely the previous commit caused a slowdown in overall performance and this fixes it. I used gcc 7.3.1. Does anybody else see this? time ffprobe -show_packets samples/ffmpeg-bugs/trac/ticket6132/Samsung_HDR_-_Chasing_the_Light.ts > /dev/null Before: real 0m2,010s user 0m1,413s sys 0m0,596s After: real 0m1,948s user 0m1,355s sys 0m0,592s Signed-off-by: Marton Balint <cus@passwd.hu> --- libavformat/mpegts.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)