Date: Tue, 26 Apr 2005 18:43:46 +0200 From: Marc Olzheim <marcolz@stack.nl> To: Brian Fundakowski Feldman <green@freebsd.org> Cc: freebsd-stable@freebsd.org Subject: Re: NFS client/buffer cache deadlock Message-ID: <20050426164346.GA68763@stack.nl> In-Reply-To: <20050426162549.GD5789@green.homeunix.org> References: <20050420140409.GA77731@stack.nl> <20050420142448.GH1157@green.homeunix.org> <20050420143842.GB77731@stack.nl> <16998.36437.809896.936800@khavrinen.csail.mit.edu> <20050420173859.GA99695@stack.nl> <20050426140701.GB5789@green.homeunix.org> <20050426151751.GB68038@stack.nl> <20050426155043.GC5789@green.homeunix.org> <20050426160609.GA68511@stack.nl> <20050426162549.GD5789@green.homeunix.org>
next in thread | previous in thread | raw e-mail | index | archive | help
--vkogqOf2sHV7VnPd Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable [changed cc: from standards@ back to stable@ again.] On Tue, Apr 26, 2005 at 12:25:49PM -0400, Brian Fundakowski Feldman wrote: > You can assure that this happens in only two ways: >=20 > 1. Make a complete copy of the data. This is what currently occurs: > it gets stuffed into the buffer cache as the write happens. > 2. Keep the data around synchronously -- by virtue of the write system > call being used synchronously, the thread's VM context is around, > and duplication need not occur. It seems as though FreeBSD 4.x either used 2) or does something wrong indeed. Why would 2) be a problem on FreeBSD 5.x ? Can't the pages written from be locked during the write, instead of copied internally ? Btw. running the writev program with 20 * 100 MB on UFS on a 512MB FreeBSD 6-CURRENT system practicly locks the filesystem down _and_ causes all processes to be swapped out in favor of the buffer cache. 'top' however, doesnt' show a rise in BUF usage. On FreeBSD 4.x, the system performance as usual during the writev to UFS. Marc --vkogqOf2sHV7VnPd Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (FreeBSD) iD8DBQFCbm/CezjnobFOgrERApvZAJ4n5oSpzvx/zSXRgt0L6jnNtT/d0QCeP6qN is4VNKkHnh0etRUkLs9ToxI= =yyIM -----END PGP SIGNATURE----- --vkogqOf2sHV7VnPd--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20050426164346.GA68763>