Date: Mon, 28 Apr 1997 10:21:37 +0100 (BST) From: Doug Rabson <dfr@nlsystems.com> To: Poul-Henning Kamp <phk@dk.tfs.com> Cc: current@freebsd.org Subject: Re: vnode->v_usage Message-ID: <Pine.BSF.3.95q.970428101839.346I-100000@herring.nlsystems.com> In-Reply-To: <4914.862168293@critter>
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On Sun, 27 Apr 1997, Poul-Henning Kamp wrote: > >I think it is intended to be used to keep frequently used vnodes from > >being recycled by getnewvnode. The idea is that whenever a vnode is found > >as a hit in the cache, its usage is increased. When getvnode picks a > >vnode off the front of the free list, it checks the usage and if >0 it > >decrements it, puts it at the back of the queue and goes onto the next > >one. This means that the lifetime of commonly used vnodes is extended. I > >don't know why it is clamped; possibly to put an upper bound on the > >lifetime of the vnode when it stops being used so frequently. > > Wouldn't it make more sense to use a LRU algorithm then ? > > As far as I recall we already add things to either end of the vnode > freelist, depending on the reusability of it, right ? > > So if vfs_cache.c simply pulled the vnode out of the free_list and > put it back at the tail, wouldn't that work ? Yes, I think that would work just as well and be less obscure as a result. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. Phone: +44 181 951 1891
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