From owner-cvs-src@FreeBSD.ORG Fri Sep 30 01:30:02 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 874DF16A420; Fri, 30 Sep 2005 01:30:02 +0000 (GMT) (envelope-from truckman@FreeBSD.org) Received: from repoman.freebsd.org (repoman.freebsd.org [216.136.204.115]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3707343D4C; Fri, 30 Sep 2005 01:30:02 +0000 (GMT) (envelope-from truckman@FreeBSD.org) Received: from repoman.freebsd.org (localhost [127.0.0.1]) by repoman.freebsd.org (8.13.1/8.13.1) with ESMTP id j8U1U2X7098516; Fri, 30 Sep 2005 01:30:02 GMT (envelope-from truckman@repoman.freebsd.org) Received: (from truckman@localhost) by repoman.freebsd.org (8.13.1/8.13.1/Submit) id j8U1U2nb098515; Fri, 30 Sep 2005 01:30:02 GMT (envelope-from truckman) Message-Id: <200509300130.j8U1U2nb098515@repoman.freebsd.org> From: Don Lewis Date: Fri, 30 Sep 2005 01:30:02 +0000 (UTC) To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org X-FreeBSD-CVS-Branch: HEAD Cc: Subject: cvs commit: src/sys/kern vfs_bio.c vfs_subr.c src/sys/sys buf.h proc.h src/sys/ufs/ffs ffs_snapshot.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: Fri, 30 Sep 2005 01:30:02 -0000 truckman 2005-09-30 01:30:01 UTC FreeBSD src repository Modified files: sys/kern vfs_bio.c vfs_subr.c sys/sys buf.h proc.h sys/ufs/ffs ffs_snapshot.c Log: Un-staticize runningbufwakeup() and staticize updateproc. Add a new private thread flag to indicate that the thread should not sleep if runningbufspace is too large. Set this flag on the bufdaemon and syncer threads so that they skip the waitrunningbufspace() call in bufwrite() rather than than checking the proc pointer vs. the known proc pointers for these two threads. A way of preventing these threads from being starved for I/O but still placing limits on their outstanding I/O would be desirable. Set this flag in ffs_copyonwrite() to prevent bufwrite() calls from blocking on the runningbufspace check while holding snaplk. This prevents snaplk from being held for an arbitrarily long period of time if runningbufspace is high and greatly reduces the contention for snaplk. The disadvantage is that ffs_copyonwrite() can start a large amount of I/O if there are a large number of snapshots, which could cause a deadlock in other parts of the code. Call runningbufwakeup() in ffs_copyonwrite() to decrement runningbufspace before attempting to grab snaplk so that I/O requests waiting on snaplk are not counted in runningbufspace as being in-progress. Increment runningbufspace again before actually launching the original I/O request. Prior to the above two changes, the system could deadlock if enough I/O requests were blocked by snaplk to prevent runningbufspace from falling below lorunningspace and one of the bawrite() calls in ffs_copyonwrite() blocked in waitrunningbufspace() while holding snaplk. See Revision Changes Path 1.495 +3 -3 src/sys/kern/vfs_bio.c 1.648 +2 -1 src/sys/kern/vfs_subr.c 1.190 +1 -0 src/sys/sys/buf.h 1.436 +1 -1 src/sys/sys/proc.h 1.104 +16 -4 src/sys/ufs/ffs/ffs_snapshot.c