Date: Tue, 13 Nov 2001 15:13:29 +0000 From: David Malone <dwmalone@maths.tcd.ie> To: Eugene Grosbein <eugen@grosbein.pp.ru> Cc: stable@freebsd.org, hackers@freebsd.org Subject: Re: kern.vm.kmem.size Message-ID: <20011113151329.A44837@walton.maths.tcd.ie> In-Reply-To: <20011111230817.A2325@grosbein.pp.ru>; from eugen@grosbein.pp.ru on Sun, Nov 11, 2001 at 11:08:17PM %2B0700 References: <20011111230817.A2325@grosbein.pp.ru>
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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-stable" in the body of the message
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