From owner-freebsd-hackers Tue Nov 13 7:13:44 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from salmon.maths.tcd.ie (salmon.maths.tcd.ie [134.226.81.11]) by hub.freebsd.org (Postfix) with SMTP id 286AB37B405; Tue, 13 Nov 2001 07:13:34 -0800 (PST) Received: from walton.maths.tcd.ie by salmon.maths.tcd.ie with SMTP id ; 13 Nov 2001 15:13:33 +0000 (GMT) Date: Tue, 13 Nov 2001 15:13:29 +0000 From: David Malone To: Eugene Grosbein Cc: stable@freebsd.org, hackers@freebsd.org Subject: Re: kern.vm.kmem.size Message-ID: <20011113151329.A44837@walton.maths.tcd.ie> References: <20011111230817.A2325@grosbein.pp.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <20011111230817.A2325@grosbein.pp.ru>; from eugen@grosbein.pp.ru on Sun, Nov 11, 2001 at 11:08:17PM +0700 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Sun, Nov 11, 2001 at 11:08:17PM +0700, Eugene Grosbein wrote: > I'm trying to test and tune speed of freebsd's filesystem in many aspects. > I run recent FreeBSD 4.4-STABLE with new dirprefs code, read tuning(7), > newfs'd my FS, turned softupdates on, have UFS_DIRHASH kernel option. > Also, I've read DIRHASH kernel code source. It seems that efficiency of > DIRHASH greatly depends of kernel memory size (and some experiments > approve this). You should be able to control how much memory is used by dirhash with the vfs.ufs.dirhash_maxmem sysctl. By default it uses up to 2MB and it should be possible to raise it significantly, providing you have enough physical memory. (By default there is about 1GB of kernel address space, so you are unlikely to be running into this limit - I don't think changing kern.vm.kmem.size will help you). Remember - raising it will only help you if your working set of oversized directories is larger that what fits into the memory allocated for dirhash. I'd suggest that you watch how much memory dirhash is using "vmstat -m" and examinign the dirhash line. David. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message