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Date:      Fri, 29 Aug 2008 08:53:00 +1000
From:      Andrew Reilly <areilly@bigpond.net.au>
To:        =?utf-8?B?6YKx5YmR?= <qj@huawei.com>
Cc:        freebsd-multimedia@freebsd.org, freebsd-arch@freebsd.org
Subject:   Re: SCHED_ULE problem: slow single processor, realtime prio vs network stack
Message-ID:  <20080828225300.GA51771@duncan.reilly.home>
In-Reply-To: <20080828071804.GA54269@duncan.reilly.home>
References:  <20080827233831.GA16705@duncan.reilly.home> <000c01c908db$f78d9180$01000001@china.huawei.com> <20080828071804.GA54269@duncan.reilly.home>

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On Thu, Aug 28, 2008 at 05:18:04PM +1000, Andrew Reilly wrote:
> Hi Jian,
> 
> On Thu, Aug 28, 2008 at 03:01:59PM +0800, 邱剑 wrote:
> > I found the network interrupt thread might take too long to run if
> > net.isr.direct=1
> > 
> > I suspect your problem might be because the network kernel thread spend so
> > long time that the sound interrupt could not find time slot to process.
> 
> That sounds like what I think is happening, but I'm still
> curious about why the same network stack manaages to be
> interrupted by the audio driver when running the 4BSD scheduler,
> but not the ULE sheduler.
> 
> > You might just try to turn netisr off when running ULE
> > 
> > sysctl -w net.isr.direct=0
> 
> I'll give that a try, as soon as possible.

As promised to Jian, here's my report on how or whether that
helped: no.  If anything, it seemed to make the network-induced
breakup of the audio timing a little worse, but I did no
measurements to verify that impression.  Thanks for the
suggestion, though.

Cheers,

Andrew



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