From owner-cvs-src@FreeBSD.ORG Sun Jun 12 10:07:08 2005 Return-Path: X-Original-To: cvs-src@freebsd.org Delivered-To: cvs-src@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 84D2816A41C; Sun, 12 Jun 2005 10:07:08 +0000 (GMT) (envelope-from bright@elvis.mu.org) Received: from elvis.mu.org (elvis.mu.org [192.203.228.196]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5A52C43D1D; Sun, 12 Jun 2005 10:07:08 +0000 (GMT) (envelope-from bright@elvis.mu.org) Received: by elvis.mu.org (Postfix, from userid 1192) id 249E35CAD9; Sun, 12 Jun 2005 03:07:08 -0700 (PDT) Date: Sun, 12 Jun 2005 03:07:08 -0700 From: Alfred Perlstein To: Brian Fundakowski Feldman Message-ID: <20050612100708.GK17867@elvis.mu.org> References: <200506102350.j5ANofFM008212@repoman.freebsd.org> <20050611034930.GY17867@elvis.mu.org> <20050611064956.GC66188@green.homeunix.org> <20050611141021.GD17867@elvis.mu.org> <20050611170425.GD66188@green.homeunix.org> <20050611174617.GE17867@elvis.mu.org> <20050611212534.GE66188@green.homeunix.org> <20050612080833.GJ17867@elvis.mu.org> <20050612082612.GF66188@green.homeunix.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050612082612.GF66188@green.homeunix.org> User-Agent: Mutt/1.4.2.1i Cc: cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/nfsclient nfs_bio.c nfs_vfsops.c nfsargs.h nfsmount.h src/sys/sys buf.h bufobj.h src/sys/kern vfs_bio.c X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 12 Jun 2005 10:07:08 -0000 * Brian Fundakowski Feldman [050612 01:26] wrote: > On Sun, Jun 12, 2005 at 01:08:33AM -0700, Alfred Perlstein wrote: > > > > Seriously, have you tested what happens to a libc_r app that > > opens an nfs file F_SYNC? My guess is that it's not pretty. > > This code path is related to O_NONBLOCK, not O_FSYNC. O_FSYNC is > synonymous with the slow fallback path that large transactional block > now takes, rather than deadlocking. O_NONBLOCK really means that > whatever they do, they are required to check for EAGAIN. To make it perfectly clear. If an application linked against libc_r opens a file with O_FSYNC. Libc_r will set O_NONBLOCK (it does so for each open(2)) A write on that descriptor will return EAGAIN (to libc_r) Libc_r will then attempt to select(2) on this decriptor, which will return "ready" (as do all select(2)'s on disk files) The question is: Will Libc_r then busy spin? If so, how many other apps might get screwed just sometimes (over nfs) because only _half_ of this "solution" is implemented? Or is my thinking on this wrong? -- - Alfred Perlstein - email: bright@mu.org cell: 408-480-4684