From owner-freebsd-performance@FreeBSD.ORG  Tue Oct  6 04:15:35 2009
Return-Path: <owner-freebsd-performance@FreeBSD.ORG>
Delivered-To: freebsd-performance@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 92757106568F
	for <freebsd-performance@freebsd.org>;
	Tue,  6 Oct 2009 04:15:35 +0000 (UTC)
	(envelope-from freebsd@sopwith.solgatos.com)
Received: from sopwith.solgatos.com
	(pool-173-50-131-36.ptldor.fios.verizon.net [173.50.131.36])
	by mx1.freebsd.org (Postfix) with ESMTP id 550568FC20
	for <freebsd-performance@freebsd.org>;
	Tue,  6 Oct 2009 04:15:34 +0000 (UTC)
Received: by sopwith.solgatos.com (Postfix, from userid 66)
	id 726C8B64F; Mon,  5 Oct 2009 21:11:21 -0700 (PDT)
Received: from localhost by sopwith.solgatos.com (8.8.8/6.24)
	id QAA06722; Mon, 5 Oct 2009 16:05:49 GMT
Message-Id: <200910051605.QAA06722@sopwith.solgatos.com>
To: freebsd-performance@freebsd.org
In-reply-to: Your message of "Mon, 05 Oct 2009 10:45:48 +0200."
	<E316139E-FFCF-432F-8DCE-62B120C38E55@exscape.org> 
Date: Mon, 05 Oct 2009 09:05:49 PDT
From: Dieter <freebsd@sopwith.solgatos.com>
Subject: ZFS  Re: A specific example of a disk i/o problem 
X-BeenThere: freebsd-performance@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Performance/tuning <freebsd-performance.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-performance>,
	<mailto:freebsd-performance-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-performance>
List-Post: <mailto:freebsd-performance@freebsd.org>
List-Help: <mailto:freebsd-performance-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-performance>,
	<mailto:freebsd-performance-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 06 Oct 2009 04:15:35 -0000

In message <E316139E-FFCF-432F-8DCE-62B120C38E55@exscape.org>, Thomas Backman writes:

> I run 8.0-RC1/amd64 with ZFS on an A64 3200+ with 2GB RAM and an old  
> 80GB 7200rpm disk.
> 
> My problem is that I get completely unacceptable latency on console IO  
> (both via SSH and serial console) when the system is performing disk  
> IO. The worst case I've noticed yet was when I tried copying a core  
> dump from a lzjb compressed ZFS file system to a gzip-9 compressed  
> one, to compare the file size/compression ratio. screen(1) took at  
> LEAST ten seconds - probably a bit more - I'm not exaggerating here -  
> to switch to another window, and an "ls" in an empty directory also  
> about 5-10 seconds.

You might find the "RELENG_7 heavy disk = system crawls" thread interesting:

} I didn't actually solve it or do anything.
} I just upgraded to RELENG_8.
}
} Now it's behaving more like FreeBSD should.
} I can do sequential reads/writes and still
} use kbd/mouse/X11/buildworld and so on.