public inbox for linux-kernel@vger.kernel.org
 help / color / mirror / Atom feed
From: Roland Dreier <rdreier@cisco.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Early hang with 2.6.21-rc4-rt1
Date: Sun, 25 Mar 2007 10:01:58 -0700	[thread overview]
Message-ID: <adavegpl0jd.fsf@cisco.com> (raw)
In-Reply-To: <ada4po9mlw5.fsf@cisco.com> (Roland Dreier's message of "Sun, 25 Mar 2007 07:35:22 -0700")

 > I finally got curious enough to want to debug why starting kvm with
 > tun/tap networking produces a bunch of
 > 
 >     rtc: lost some interrupts at 1024Hz.
 > 
 > messages.  So I'm assuming it's a ~millisecond irqs-off section
 > somewhere.

And after everything, it's a heisenbug -- I repeatably get that lost
interrupts message on stock 2.6.21-rc4 but never on -rt1 with
CONFIG_LATENCY_TRACE.

Any suggestion of where to look?  My /proc/latency_trace stays
stubbornly empty -- are there any sysctls I need to change from their
default to get latency tracing?  I'm a complete noob when it comes to
the -rt patch, so I'm not sure what the right way to use the tracing
infrastructure to track down this lost rtc interrupts issue is.

Thanks, 
  Roland

  reply	other threads:[~2007-03-25 17:02 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-03-25  5:03 Early hang with 2.6.21-rc4-rt1 Roland Dreier
2007-03-25  5:29 ` Roland Dreier
2007-03-25  7:29   ` Ingo Molnar
2007-03-25  7:34     ` Ingo Molnar
2007-03-25  8:06       ` Ingo Molnar
2007-03-25 16:27         ` Roland Dreier
2007-03-25  7:31 ` Ingo Molnar
2007-03-25 14:35   ` Roland Dreier
2007-03-25 17:01     ` Roland Dreier [this message]
2007-03-27 19:22       ` Ingo Molnar
2007-03-27 19:24       ` Ingo Molnar
2007-03-27 19:42         ` Roland Dreier
2007-03-30  9:02           ` Ingo Molnar
2007-03-30  9:24             ` Ingo Molnar

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=adavegpl0jd.fsf@cisco.com \
    --to=rdreier@cisco.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@elte.hu \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox