From owner-freebsd-stable Wed Jan 16 2:46:18 2002 Delivered-To: freebsd-stable@freebsd.org Received: from shikima.mine.nu (pc1-card4-0-cust77.cdf.cable.ntl.com [62.252.49.77]) by hub.freebsd.org (Postfix) with ESMTP id 8410037B416 for ; Wed, 16 Jan 2002 02:46:15 -0800 (PST) Received: from rasputin by shikima.mine.nu with local (Exim 3.33 #1) id 16Qncu-0000lf-00; Wed, 16 Jan 2002 10:49:04 +0000 Date: Wed, 16 Jan 2002 10:49:04 +0000 From: Rasputin To: Matthew Dillon Cc: stable@freebsd.org Subject: Re: what's vnlru? Message-ID: <20020116104904.A2800@shikima.mine.nu> Reply-To: Rasputin References: <200201151618468.SM01176@141.com> <200201160101.g0G117r64693@apollo.backplane.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <200201160101.g0G117r64693@apollo.backplane.com>; from dillon@apollo.backplane.com on Tue, Jan 15, 2002 at 05:01:07PM -0800 Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG * Matthew Dillon [020116 01:10]: > vnlru is responsible for flushing and freeing vnodes when you > hit the kern.maxvnodes limit. The history of this is: > > 4.4 and earlier vnodes were only freed if they had no cached pages. > This could lead to a vnode blowout on machines with > large amounts of ram accessing lots of small files. > (the kern.maxvnodes limit was essentially ignored) > > 4.4-stable I introduced code to flush/reuse vnodes on the fly, > but this lead to possible locking deadlocks. > > 4.5-* Peter introduced a separate kernel thread to deal with > vnode flushing issues, 'vnlru', in order to fix the > possible locking deadlocks. The on-the-fly code > was changed to only be called from the kernel thread. > > This kernel thread will generally not be very active, even on a heavily > loaded system. You have to have a lot of ram and be accessing tens of > thousands of tiny files to activate the thread. Thansk for the overview - it's not a performance issue, I just checked another fairly recent (4.5 pre) BSD box and didn't see it, so thought I'd better check it out. [ Is this the sort of thing that should go into UPDATING? ] Thanks to all ! -- Learned men are the cisterns of knowledge, not the fountainheads. Rasputin :: Jack of All Trades - Master of Nuns :: To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message