From owner-freebsd-bugs@FreeBSD.ORG Wed Jan 16 19:00:07 2008 Return-Path: Delivered-To: freebsd-bugs@hub.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 5B13416A421 for ; Wed, 16 Jan 2008 19:00:07 +0000 (UTC) (envelope-from gnats@FreeBSD.org) Received: from freefall.freebsd.org (freefall.freebsd.org [IPv6:2001:4f8:fff6::28]) by mx1.freebsd.org (Postfix) with ESMTP id 4950913C4CC for ; Wed, 16 Jan 2008 19:00:07 +0000 (UTC) (envelope-from gnats@FreeBSD.org) Received: from freefall.freebsd.org (gnats@localhost [127.0.0.1]) by freefall.freebsd.org (8.14.2/8.14.2) with ESMTP id m0GJ07ME061708 for ; Wed, 16 Jan 2008 19:00:07 GMT (envelope-from gnats@freefall.freebsd.org) Received: (from gnats@localhost) by freefall.freebsd.org (8.14.2/8.14.1/Submit) id m0GJ07d9061707; Wed, 16 Jan 2008 19:00:07 GMT (envelope-from gnats) Date: Wed, 16 Jan 2008 19:00:07 GMT Message-Id: <200801161900.m0GJ07d9061707@freefall.freebsd.org> To: freebsd-bugs@FreeBSD.org From: Thomas Hurst Cc: Subject: Re: kern/114438: [amr] Anomalous performance with multiple arrays and amr(4) X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Thomas Hurst List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 16 Jan 2008 19:00:07 -0000 The following reply was made to PR kern/114438; it has been noted by GNATS. From: Thomas Hurst To: bug-followup@FreeBSD.org Cc: Subject: Re: kern/114438: [amr] Anomalous performance with multiple arrays and amr(4) Date: Wed, 16 Jan 2008 18:33:55 +0000 Further investigation would seem to implicate atime updates; every time reads from one array freeze, the other array has an IO queue depth (as reported by gstat) of ~1000 and is performing a bunch of writes. Ignoring the meta-issue of all those atime updates, it would seem the large work queue to one array on the card starves out other arrays. My recent tests for this have been on 7.0-RC1 as of today. -- Thomas 'Freaky' Hurst http://hur.st/