Date: Sun, 27 Apr 1997 17:07:43 -0400 (EDT) From: Peter Dufault <dufault@hda.com> To: dfr@nlsystems.com (Doug Rabson) Cc: current@freebsd.org Subject: Re: vnode->v_usage Message-ID: <199704272107.RAA14375@hda.hda.com> In-Reply-To: <Pine.BSF.3.95q.970427143216.346G-100000@herring.nlsystems.com> from Doug Rabson at "Apr 27, 97 02:36:36 pm"
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> 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. Warning: I'm going strictly by your description without looking at the code, but instead of clamping to avoid "integrator windup" put the cache-hit vnode at the tail of the queue. Peter -- Peter Dufault (dufault@hda.com) Realtime Machine Control and Simulation HD Associates, Inc. Voice: 508 433 6936
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