[linux-audio-dev] Low latency and X11 Direct Rendering

New Message Reply About this list Date view Thread view Subject view Author view Other groups

Subject: [linux-audio-dev] Low latency and X11 Direct Rendering
From: Enrique Robledo Arnuncio (erobledo_AT_iua.upf.es)
Date: Wed Jun 05 2002 - 20:40:28 EEST


Hi!

Running latencytest I have found a quite bad behaviour with the high
X11 load test when the X server has the DRI module loaded and active.

Is anyone there using DRI and lowlatency-patch at the same time?

Have you experienced this kind of problems?

Any known solution? I use OpenGL for real time visualization of audio,
and it is not nice if I need to disable HW accel!!!

Regards,

  Enrique.

---- Some output from latencytest:

Using 3x512 fragmets, with DRI loaded and direct rendering active, I
got:

> fragment latency = 2.902494 ms
> cpu latency = 2.321995 ms
> 8.1ms ( 80)|
> 1MS num_time_samples=23155 num_times_within_1ms=22451 factor=96.959620
> 2MS num_time_samples=23155 num_times_within_2ms=22451 factor=96.959620

Or in other words, 3% frame dropouts...

After removing the load "dri" line from the XF86Config-4, it goes
fine:

> fragment latency = 2.902494 ms
> cpu latency = 2.321995 ms
> 3.3ms ( 0)|
> 1MS num_time_samples=21477 num_times_within_1ms=21477 factor=100.000000
> 2MS num_time_samples=21477 num_times_within_2ms=21477 factor=100.000000

Or in other words, clean sound, and a beautiful latency graph.

I have tried a few times, just commenting and uncommenting the 'load
"dri"' line, and the results are always almost identical.

---- System Info:

* kernel 2.4.17 with
     ** SMP disabled
     ** Andrew Morton's low latency patch active.
     ** agpgart active (VIA chipset)
     ** mga drm driver active.

* ALSA 0.9.0rc1.

* latencytest0.42-png

* XFree86 version: 4.1.0.1
    ** mga driver
    ** GLX Direct Rendering working when DRI is loaded.

* Processor: Dual Pentium III 800, (I did this tests with SMP disabled
  in kernel).

* G. Card: Matrox Graphics, Inc. MGA G400 AGP (rev 04)

* S. Card: Ensoniq ES1371 [AudioPCI-97] (rev 08)

* AGP chipset: VIA Technologies, Inc. VT82C598/694x [Apollo MVP3/Pro133x AGP]


New Message Reply About this list Date view Thread view Subject view Author view Other groups

This archive was generated by hypermail 2b28 : Wed Jun 05 2002 - 21:34:41 EEST