Date: Wed, 8 Apr 2009 16:24:36 +0200 From: Attilio Rao <attilio@freebsd.org> To: Robert Watson <rwatson@freebsd.org> Cc: svn-src-stable@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, svn-src-stable-7@freebsd.org, Stephen McKay <mckay@freebsd.org> Subject: Re: svn commit: r190837 - in stable/7/sys: . contrib/pf dev/ath/ath_hal dev/cxgb kern Message-ID: <3bbf2fe10904080724i381c36fdpb1699def955fdb6d@mail.gmail.com> In-Reply-To: <alpine.BSF.2.00.0904081500220.61921@fledge.watson.org> References: <200904080430.n384UGWw043589@svn.freebsd.org> <alpine.BSF.2.00.0904081500220.61921@fledge.watson.org>
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2009/4/8, Robert Watson <rwatson@freebsd.org>: > On Wed, 8 Apr 2009, Stephen McKay wrote: > > > > Author: mckay > > Date: Wed Apr 8 04:30:16 2009 > > New Revision: 190837 > > URL: http://svn.freebsd.org/changeset/base/190837 > > > > Log: > > MFC r187460: Add a limit on namecache entries. > > > > Obviously, having a limit is a good idea, but I wonder if we should use > some more mature scheme to limit entries. At the very least, using UMA zone > limits may help memory being dedicated to cache entries without being able > to actually use it (i.e., extra entries in the UMA cache above the > desiredvnodes limit). > > Similarly, the cost of different cache entries is different -- long entries > cost much, much more than short ones, because we use two bucket sizes. > Perhaps this means that we should separately count long and short entries, > and short ones should contribute less towards the limit than long ones? > > Finally, I think it would be a good idea to do a bit of real-world > profiling on memory efficiency of the name cache: how much memory is wasted > when assumptions about short/long are wrong, and could we retune lengths, > limits, hash bucket counts, etc, to work better in practice? Am I wrong or you were working on adding DTrace tracing to it? Do you have any interesting workload/numbers you can show? Thanks, Attilio -- Peace can only be achieved by understanding - A. Einstein
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