[LAU] 64-bit improves audio performance?

From: Jonathan E. Brickman <jeb@email-addr-hidden>
Date: Fri Dec 18 2009 - 06:50:47 EET

Well. No change in Jack behavior with LXDE, no change from total
removal of Pulse. Now I really wonder. 64-bit has definitely upped my
GUI speed, often tripled my WWW speed -- but it has either not touched
audio (synth and Jack) performance and latency, or has hurt it
slightly! Anyone seen the same thing?

J.E.B.

>>> Should CONFIG_HPET_EMULATE_RTC be set to n on a realtime kernel? Is
>>> there something else which might invalidate CONFIG_HPET=y ?
>>>
>>>
>> the RTC device is unrelated to HPET. your kernel can have HPET support
>> but if your h/w doesn't, you don't get /dev/hpet. My motherboard, for
>> example, does not have an HPET device.
>>
>>
> That is interesting. I am interested principally because I'm seeing
> xruns and am hunting for causes, and that stood out.
>
> Checked the BIOS; HPET is there, already turned on. Running the
> vanilla-install Debian Testing (AMD64) kernel, package
> "linux-image-2.6.30-2-amd64" version 2.6.30-8, I do have a /dev/hpet.
> Running any of six or seven slightly different but very clean rtlinux
> builds (vanilla kernel source of 2.6.31.6, plus rtlinux
> patch-2.6.31.6-rt19.bz2), .config options verified and reverified very
> carefully, I don't have a /dev/hpet. Anything I should check? Do you
> think I should get on a kernel dev list?
>
> But I understand now that hpet may have little or nothing to do with the
> xrun problem. At least part of the symptomatology, is that Pulse
> talking to Jack on 64-bit Debian Testing / Gnome with GUI sound events
> off, seems to eat a whole lot more of Jack's DSP capacity than the same
> combination on 32-bit / LXDE. On 32-bit, Pulse at idle ate zero CPU;
> now on 64-bit, Pulse at idle is eating about 2%. I'm wondering right
> this minute if Gnome keeps its default sound open, delivering full-bore
> (albeit silent) audio even when it's told not to do so.
>
> I suppose I'll try LXDE. But any suggestions will be very much appreciated.
>
> J.E.B.
>
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>

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Received on Fri Dec 18 08:15:01 2009

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