[ardour-dev] Latency: AGP vs PCI video card and XFS journalling vs not
Tommi Sakari Uimonen
tuimonen at cc.hut.fi
Mon Feb 23 01:10:33 PST 2004
> beta9+3) with a 2.6.3 kernel and have played around w/ all the
Try 2.4 series with lowlatency & preemtive patches. AIUI, 2.4+ll+pe is
still better than any 2.6.
> standard latency issues (no extra stuff running, swapped PCI cards
> around for interrupts, etc.). However, I'm not able to go lower than
irq 9 would be best for soundcard. The irq order for non-apic system is,
from highest priority to lowest: 1,8,9,10,11,12,13,14,15,3,4,5,6,7
> 2. Could it be my XFS filesystems? If I have 8 or so tracks on one
> drive, it can't even handle playback w/o giving disk errors. I've
> tweaked all the XFS options, and currently have a large (64MB) log for
> each filesystem that resides on the opposite disk. Would turning the
> log size up or down help? Is there a way to just turn off journalling
> in XFS, or would ext2 be better? I did notice that exporting to my
> default param (i.e. small log) ext3 root partition seems to be faster
> than to my XFS.
For recording purposes, "write as much as possible, as fast as possible",
(so no reading other tracks at the same time, just writing) I found ext2
to be fastest (ext3,reiserfs were included in the test), since it doesn't
spend time journaling.
Actually I tested this with my MiniDV, which gives 25MBits/s through
firewire, which corresponds roughly to 11 channels of 24/96.
So this test was only about disk performance, not JACK+Soundcard involved.
But as a conclusion from the results, I used ecasound with 10 channels of
24/96 (stored the data as 32bit) to ext2 and never got any
I don't know if ext2 is good for simultaneous r/w, nor ext3 and reiserfs
for this matter.
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