From owner-freebsd-current@FreeBSD.ORG Thu May 5 20:56:06 2011 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id C79AF10657DA for ; Thu, 5 May 2011 20:56:06 +0000 (UTC) (envelope-from mavbsd@gmail.com) Received: from mail-fx0-f54.google.com (mail-fx0-f54.google.com [209.85.161.54]) by mx1.freebsd.org (Postfix) with ESMTP id 4EED58FC12 for ; Thu, 5 May 2011 20:56:05 +0000 (UTC) Received: by fxm11 with SMTP id 11so2517632fxm.13 for ; Thu, 05 May 2011 13:56:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:sender:message-id:date:from:user-agent :mime-version:to:cc:subject:references:in-reply-to :x-enigmail-version:content-type:content-transfer-encoding; bh=I15OTGoYQbSQ3omxBx/ld/JAML1mUGfP3zUuHPWJpC8=; b=iNpbM2rnFl05CvopIoDMX0EevmPHg/rv8S0QPlR6+YfCb2XhSh6+HbNdUBUHdi1zFF m1bw4Tm7LAG/MkUtIYHLEepyJZ6VCfCQ9GGet7boPmAWMFw27bM5SOQaVZgOSGqnDP5p O/E4ftescACIw8xPJOejJBNYOsp0SQgg9A2fc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:x-enigmail-version:content-type :content-transfer-encoding; b=gQ11YxwWQTDHFq3JE8745AX+Y+4a6aD8bl78s0Z9vfZ69zXR2ROjc8WcXLTWzgJ77/ tz094AohleLIPSWOXMKFm4lmM0P8NLMPPAKD9DgBuVfULKQE9wl6fO401PeMjSSJsZSz OXpOG6gRVzy5m3XUaJKe+YMC7w2mvbc2wYMZw= Received: by 10.223.75.15 with SMTP id w15mr3199345faj.134.1304628964927; Thu, 05 May 2011 13:56:04 -0700 (PDT) Received: from mavbook2.mavhome.dp.ua (pc.mavhome.dp.ua [212.86.226.226]) by mx.google.com with ESMTPS id j11sm869244faa.44.2011.05.05.13.56.03 (version=SSLv3 cipher=OTHER); Thu, 05 May 2011 13:56:04 -0700 (PDT) Sender: Alexander Motin Message-ID: <4DC30EC5.3090703@FreeBSD.org> Date: Thu, 05 May 2011 23:55:33 +0300 From: Alexander Motin User-Agent: Thunderbird 2.0.0.23 (X11/20091212) MIME-Version: 1.0 To: Doug Barton References: <4DC25396.1070909@dougbarton.us> In-Reply-To: <4DC25396.1070909@dougbarton.us> X-Enigmail-Version: 0.96.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: freebsd-current@FreeBSD.org Subject: Re: My problems with stability on -current X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 05 May 2011 20:56:07 -0000 Doug Barton wrote: > Alexander suggested some knobs to twist for the timers, and I'll be glad > to do that once he gets back to me with more concrete suggestions now > that he knows more about my specific problems. OK, I am all here. While this post is indeed larger then previous, it is not much more informative. Sorry. :( I see several possibly unrelated problems there: - crashes are always crashes. They should be debugged. - calcru going backwards could have the same roots as lost wall clock time. If there are some problems with timer interrupts, timecounters could wrap unnoticed that will cause random time jumps. - interactivity problems. I can't prove it is unrelated, but have no real ideas now. I would start from most obvious problems. I need to know more about crashes. As usual: how to trigger, stack backtraces, etc. What's about time problems, I would try to collect more data: - show `sysctl kern.eventtimer`, `sysctl kern.timecounter` and verbose dmesg outputs; - what eventtimer is used now and does it helps to switch to another one with kern.eventtimer.timer sysctl? - does the timer runs in periodic or one-shot mode and does it helps to switch to another one? - if full CPU load makes time to stop, try to track what is going on with timer interrupts using `vmstat -i` and `systat -vm 1`. Under full CPU load in one-shot mode you should have stable timer interrupt rate about hz+stathz. - if timer interrupts are not working well, you can build kernel with options KTR options ALQ options KTR_ALQ options KTR_COMPILE=(KTR_SPARE2) options KTR_ENTRIES=131072 options KTR_MASK=(KTR_SPARE2) to track event timers operation and use ktrdump to save the trace when problem exist (preferably when it begins). And let's experiment with fresh CURRENT. -- Alexander Motin