Re: [LAU] Freebob high CPU usage

Thanks for your responses,

I was comparing same latency settings, but it's true, it's unfair to
compare a two channel interface with a 10+midi one.

Pieter: I'm using jack and freebob from the Ubuntu repositories
(libfreebob0 version 1.0.7-1). Is that a debug build?

Regards,

Hector

On Sun, Sep 21, 2008 at 5:24 AM, Pieter Palmers <pieterp@email-addr-hidden> wrote:
> hollunder@email-addr-hidden wrote:
>> On Sun, 21 Sep 2008 01:06:21 -0400
>> "Hector Centeno" <hcengar@email-addr-hidden> wrote:
>>
>>> Hello,
>>>
>>> I have two computers (desktop and laptop) with Ubuntu Hardy (using
>>> kernel RT on both) and a Edirol FA-101 firewire interface. I was
>>> comparing Jack's CPU usage (no other audio app running) using the
>>> Edirol against a USB M-Audio Transit. I noticed on both computer the
>>> CPU usage to be much higher with the firewire interface than with the
>>> USB. On my laptop goes up to 15% or more and 8% on my desktop
>>> (Centrino Duo @ 1.7GHz and Core 2 Duo @ 2.1 GHz respectively) while
>>> using the USB interface the usage remains below 1%. Is this a normal
>>> behaviour of firewire interfaces? Is this a Jack related issue? Is
>>> there a recent and more efficient version of Freebob (ffado maybe?)
>>> than the one from the Ubuntu repos?
>>>
>>> Cheers,
>>>
>>> Hector
>>
>> Are you sure that you are comparing the same latency settings? Just
>> a thought because Firewire is capable of lower latencies than USB and
>> lower latencies also mean higher cpu usage.
>> As said, just a thought, I never used FW.
>
> This is partially true.
>
> The fact that the transit has only a channel count of 2in/4out while the
> FA-101 has 10in/10out + midi makes that it's not really a fair comparison.
>
> However the main issue is that the kernel-space firewire implementation
> is not very CPU efficient. There are some issues with how DMA memory
> coherence is implemented that make things CPU intensive. Messing with
> the kernel level implementation to improve CPU consumption is not
> considered a priority for the freebob/ffado developers ATM. The 'new'
> firewire kernel drivers will allow us to implement a more efficient
> scheme reducing CPU. But let's first get the current FFADO out.
>
> FreeBoB/FFADO themselves are fairly CPU efficient, although things can
> always be improved.
>
> Greets,
>
> Pieter
>
> PS: you don't by any chance use a freebob/ffado debug build?
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Received on Mon Sep 22 04:15:01 2008