From: Lee Revell <rlrevell@joe-job.com>
To: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
Cc: jackit-devel <jackit-devel@lists.sourceforge.net>,
Ingo Molnar <mingo@elte.hu>,
William Lee Irwin III <wli@holomorphy.com>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [Jackit-devel] Re: xruns
Date: Sun, 08 Aug 2004 00:58:27 -0400 [thread overview]
Message-ID: <1091941106.1183.76.camel@mindpipe> (raw)
In-Reply-To: <20040807222832.GA29571@login.ecs.soton.ac.uk>
On Sat, 2004-08-07 at 18:28, Steve Harris wrote:
> On Sat, Aug 07, 2004 at 06:01:16 -0400, Lee Revell wrote:
> > I have not found a good solution to this issue. It's possibe that this
> > is an ALSA bug, though Steve Harris says this xrun is inevitable. I am
> > not sure I understand why.
>
It looks like this one is actually real, because when I use the
preempt-timing patch it corresponds to a report of a 10ms
non-preemptible section. get_user_pages appears to be the offender.
jackd does not print an xrun report here due to this code in
alsa-driver.c:
/* Delay (in process calls) before jackd will report an xrun */
#define XRUN_REPORT_DELAY 64
...
if (snd_pcm_status_get_state(status) == SND_PCM_STATE_XRUN
&& driver->process_count > XRUN_REPORT_DELAY) {
... print xrun errmsg ...
}
Presumably the author thought this behavior was by design.
(jackd/6566): 10952us non-preemptible critical section violated 1000 us preempt threshold starting at kmap_atomic+0x10/0x60 and ending at kunmap_atomic+0x8/0x20
[<c0106717>] dump_stack+0x17/0x20
[<c0113eec>] dec_preempt_count+0x3c/0x50
[<c0111ce8>] kunmap_atomic+0x8/0x20
[<c013e2cb>] do_anonymous_page+0x8b/0x190
[<c013e41e>] do_no_page+0x4e/0x310
[<c013e8a1>] handle_mm_fault+0xc1/0x170
[<c013d280>] get_user_pages+0x110/0x380
[<c013e9f8>] make_pages_present+0x68/0x90
[<c0140196>] do_mmap_pgoff+0x3e6/0x620
[<c010b656>] sys_mmap2+0x76/0xb0
[<c01060b7>] syscall_call+0x7/0xb
Lee
parent reply other threads:[~2004-08-08 4:58 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20040807222832.GA29571@login.ecs.soton.ac.uk>]
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