Date: Wed, 9 Apr 1997 10:30:32 +0900 (JST) From: Michael Hancock <michaelh@cet.co.jp> To: Terry Lambert <terry@lambert.org> Cc: current@FreeBSD.ORG, freebsd-fs@FreeBSD.ORG Subject: Re: DISCUSS: vnode references as open instances Message-ID: <Pine.SV4.3.95.970409101738.15376D-100000@parkplace.cet.co.jp> In-Reply-To: <Pine.SV4.3.95.970408185516.10389B-100000@parkplace.cet.co.jp>
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On Tue, 8 Apr 1997, Michael Hancock wrote: > > Though vnodes are currently globally accounted, I beleive that > > there should be a per FS interface, initially to the global > > accounting interface, for freeing vnodes in an FS specific > > manner. > > > > The eventual intent of this change is to allow per-FS management > > of vnodes as part of the FS's [*,i]node pool, and to therefore > > relieve the need for global vnode pool management, and thus global > > recovery of vnodes for reuse. > > > > One large benefit of this technique would be to allow the recovery > > of unreferenced vnodes from per FS "second chance" caches, like > > the FFS "ihash" facility, and therfore the recovery of perfectly > > valid memory pages that refere to a referenced per FS object. > > > > Currently, there is no recovery mechanism whereby the valid pages > > can be re-referenced for use once the vnode had been disassociated > > from the per-FS object, but not from the valid pages. > > > > When a reference which references these pages occurs, the data, > > though in core, cannot be reclaimed, and must be reread from > > disk. 1) Create a directory /sys/u2fs. 2) Build the necessary scaffolding, VT_U2FS, vop scripts, etc. and do the VT_TFS thing. 3) Submit updates to the /sys/u2fs directory in parcels as big as you want. 4) If your analysis is accurate, and you correctly design and implement the changes then most applications will show a significant performance improvement. 5) Get Matt Dillon, Joe Greco, and Karl to "beat the snot" out your new improved ufs and get them to make testimonials. 6) Then work on converting the VT_TFS, VT_U2FS special case the general case. Regards, Mike Hancock
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