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@xxxxxxx> wrote: > hollunder@xxxxxx wrote: >> On Sun, 21 Sep 2008 01:06:21 -0400 >> "Hector Centeno" <hcengar@xxxxxxxxx> 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? > _______________________________________________ > Linux-audio-user mailing list > Linux-audio-user@xxxxxxxxxxxxxxxxxxxx > http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user > _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user
