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From: brucee@runxtsa.runx.oz.au (Bruce Evans)
Newsgroups: comp.os.minix
Subject: Re: Recap on past 2 weeks
Message-ID: <2096@runxtsa.runx.oz.au>
Date: 4 Aug 90 19:53:19 GMT
References: <7217@star.cs.vu.nl> <641@philica.ica.philips.nl>
Organization: RUNX Unix Timeshare.  Sydney, Australia.
Lines: 15

In article <7217@star.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>When FS sends a disk driver a message, if the disk driver didn't happen to
>have the block cached internally, it could store the request in its tables,
>and return a SUSPEND message immediately.  FS would react the same way as with

This can only work for data blocks. Even then, it only solves the easy part of
the problem. Suppose user1 asks for a block not in the cache and is suspended,
then user2 asks for the same block. The second request must not get far as the
device driver, and will require a more complicated suspension method. Note
that the second request may be from a deeply nested FS function for a
directory block although the first request if for a data block.
-- 
Bruce Evans
Internet: brucee@runxtsa.runx.oz.au    UUCP: uunet!runxtsa.runx.oz.au!brucee
(My other address (evans@ditsyda.oz.au) no longer works)