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From: paul@vixie.UUCP (Paul Vixie Esq)
Newsgroups: comp.unix.wizards,comp.unix.questions
Subject: Re: SUMMARY:  Unix and SI Disk Cache Processors
Message-ID: <773@vixie.UUCP>
Date: 5 Jan 88 16:57:57 GMT
References: <3100@briar.Philips.Com> <2659@killer.UUCP>
Reply-To: paul@vixie.UUCP (Paul Vixie Esq)
Organization: Vixie Enterprises, San Francisco
Lines: 18

In article <2659@killer.UUCP> jfh@killer.UUCP (The Beach Bum) writes:
>I want to know what vendors are doing to use the memory my machine has
>to dynamically adjust the size of the disk cache?  Why aren't all those
>pages sitting on the free list being used for block buffers?

I asked that question of Erik Fair once, and he said: "beware of a sync(2)!"

I guess it would work as a write-through cache, but that's not how the
buffer system in UNIX(tm) works right now.  Presently, the disk buffers
are written out only when the sync(2) call is made or when a buffer needs
to be reused.  Imagine sync(2)'ing 16MB worth of disk data :-(.

A write-through cache would be neat, but it would also be a hell of a lot
of work.  Does anyone know of a UNIX(tm)-type kernel than does this?

--
Paul Vixie
ucbvax!dual!ptsfa!vixie!paul