From owner-freebsd-fs@FreeBSD.ORG Fri May 21 15:25:32 2010 Return-Path: Delivered-To: fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 15579106566C; Fri, 21 May 2010 15:25:32 +0000 (UTC) (envelope-from rmacklem@uoguelph.ca) Received: from esa-jnhn.mail.uoguelph.ca (esa-jnhn.mail.uoguelph.ca [131.104.91.44]) by mx1.freebsd.org (Postfix) with ESMTP id 6E8C08FC0C; Fri, 21 May 2010 15:25:31 +0000 (UTC) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AvsEAHhC9kuDaFvI/2dsb2JhbACeH3G9bYUSBA X-IronPort-AV: E=Sophos;i="4.53,278,1272859200"; d="scan'208";a="77237375" Received: from darling.cs.uoguelph.ca ([131.104.91.200]) by esa-jnhn-pri.mail.uoguelph.ca with ESMTP; 21 May 2010 11:25:29 -0400 Received: from localhost (localhost.localdomain [127.0.0.1]) by darling.cs.uoguelph.ca (Postfix) with ESMTP id A50DC9400AA; Fri, 21 May 2010 11:25:29 -0400 (EDT) X-Virus-Scanned: amavisd-new at darling.cs.uoguelph.ca Received: from darling.cs.uoguelph.ca ([127.0.0.1]) by localhost (darling.cs.uoguelph.ca [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id SwdGfZijh47V; Fri, 21 May 2010 11:25:28 -0400 (EDT) Received: from muncher.cs.uoguelph.ca (muncher.cs.uoguelph.ca [131.104.91.102]) by darling.cs.uoguelph.ca (Postfix) with ESMTP id A14C5940174; Fri, 21 May 2010 11:25:28 -0400 (EDT) Received: from localhost (rmacklem@localhost) by muncher.cs.uoguelph.ca (8.11.7p3+Sun/8.11.6) with ESMTP id o4LFeoa27571; Fri, 21 May 2010 11:40:50 -0400 (EDT) X-Authentication-Warning: muncher.cs.uoguelph.ca: rmacklem owned process doing -bs Date: Fri, 21 May 2010 11:40:50 -0400 (EDT) From: Rick Macklem X-X-Sender: rmacklem@muncher.cs.uoguelph.ca To: John Baldwin In-Reply-To: <201005200922.17245.jhb@freebsd.org> Message-ID: References: <201005191144.00382.jhb@freebsd.org> <201005200922.17245.jhb@freebsd.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: Rick Macklem , Robert Watson , fs@freebsd.org Subject: Re: [PATCH] Better handling of stale filehandles in open() in the NFS client X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 21 May 2010 15:25:32 -0000 On Thu, 20 May 2010, John Baldwin wrote: > > It doesn't change the RPC count because of changes that Mohan added to the > NFS client a while ago so that nfs_open() doesn't invalide the attribute > cache during nfs_open() if it was already updated via nfs_lookup() during > the same system call. With Mohan's changes in place, all this change does > is move the GETATTR/ACCESS RPC earlier in the case of a namecache hit. > I tried another kernel build with and without the patch and an about 6% increase in Getattr RPCs seems real. (The 1% increase in Access RPCs was not related to the patch and appears to have happened because I didn't do an unmount/mount between runs, which results in RPC cnts changing by up to 1%.) I have no idea whether or not an approx. 6% increase in Getattr RPCs for this case is enough of a concern w.r.t. patch that it needs to be looked at further? Btw, I'm doing the tests on a pretty recent -current kernel which appears to do shared vnode locks for read opens, which might explain why the Getattr cnt changes? (You're patch had quite different line #s, so I assume it wasn't against -current?) Have fun with it, rick