[lkml]   [2005]   [Sep]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: "Read my lips: no more merges" - aka Linux 2.6.14-rc1
Linus Torvalds wrote:
> On Tue, 13 Sep 2005, Mathieu Fluhr wrote:
>>Okay, here is the point: I will have these bloody buffer underruns
>>unless I select a 'Timer frequency' of 1000 Hz in 'Processor type and
>>features' section of the kernel configuration. That's quite
>>understandable, as recording a DVD at 16x requires a throughput of 22160
>>KB/s, which is quite fast.
>>I will have a deep look in the patch, and maybe write a patched patch
>>(Ooooo my god what am I writing ?) in the next few days.
> It may just be an application bug too. Too small a buffer, and depending
> on 2.6.x with a 1kHz timer having timers that run faster...

With cdrecord I can set the FIFO buffer size up to 20MB or so, which is
locked in memory when running as root. The issue seems to be moving the
data from the application buffer to the device buffer. Something in the
kernel would appear to only do that data transfer on a timer tick. It
may be that the dispatch latency is just too high, and that the thread
pushing the data to the device is just not getting the CPU in time, even
with the application buffer locked and the application running at RT

I generally build my kernels with voluntary preempt, I think I tried a
real preempt kernel without improvement, but I can't swear to it. If the
O.P. doesn't mind a 14th build that might be a decent data point.

-bill davidsen (
"The secret to procrastination is to put things off until the
last possible moment - but no longer" -me

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-09-14 17:28    [W:0.062 / U:0.520 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site