From owner-freebsd-stable@FreeBSD.ORG Wed Oct 14 11:16:59 2009 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 4EB3D1065672 for ; Wed, 14 Oct 2009 11:16:59 +0000 (UTC) (envelope-from freebsd-stable@m.gmane.org) Received: from lo.gmane.org (lo.gmane.org [80.91.229.12]) by mx1.freebsd.org (Postfix) with ESMTP id 031A78FC21 for ; Wed, 14 Oct 2009 11:16:58 +0000 (UTC) Received: from list by lo.gmane.org with local (Exim 4.50) id 1My1qi-00072o-IO for freebsd-stable@freebsd.org; Wed, 14 Oct 2009 13:16:56 +0200 Received: from lara.cc.fer.hr ([161.53.72.113]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 14 Oct 2009 13:16:56 +0200 Received: from ivoras by lara.cc.fer.hr with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 14 Oct 2009 13:16:56 +0200 X-Injected-Via-Gmane: http://gmane.org/ To: freebsd-stable@freebsd.org From: Ivan Voras Date: Wed, 14 Oct 2009 13:16:29 +0200 Lines: 21 Message-ID: References: <9bbcef730910130633w150571a0k461fb4e67a51fb1d@mail.gmail.com> <9bbcef730910131057i71db846et1f0d4aeadef5e302@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: lara.cc.fer.hr User-Agent: Thunderbird 2.0.0.23 (X11/20090928) In-Reply-To: Sender: news Subject: Re: Extreme console latency during disk IO (8.0-RC1, previous releases also affected according to others) X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 14 Oct 2009 11:16:59 -0000 Larry Rosenman wrote: > On Tue, 13 Oct 2009, Ivan Voras wrote: >> As for what data is needed, it depends on what you can get - from this >> discussion thread it looks like it would be enough to verify that disk >> IO doesn't leave VM processes waiting (i.e. that disk IO doesn't >> interfere with CPU-bound or idle virtual machines). Though now when I >> think of it - doesn't Linux ATA driver poll IO in some funky way, >> expecting to get lower latency that way? >> > Have you looked at the information available via the performance tab(s) > in the > client pointing at the ESXi server? The 20 second time resolution I get in performance charts isn't nearly enough to diagnose something like this. I've now been running iostat in the virtual console (not ssh) during disk IO and I can't seem to get the characteristic "stutter" / pause behaviour so I think that it's very likely there is too much going on in the VM software to accurately conclude anything.