Date: Sun, 22 Aug 1999 10:24:16 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Maxim Sobolev <sobomax@altavista.net> Cc: current@FreeBSD.ORG Subject: Re: Sync(8) doesn't have any effect on softupdates-enabled filesystem Message-ID: <199908221724.KAA80221@apollo.backplane.com> References: <37BFD2E4.370EA4A4@altavista.net>
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:I do not know if it is bug or feature, but it seems that sync(8) command
:doesn't really flushing write buffers for softdep enabled f/s. IMHO this
:behavior is not very friendly for the notebooks and ATX owners because
:before putting computer into sleep mode OS preferably should try to
:write as many as possible unflushed buffers to disk (see
:/etc/rc.suspend). Following is simple showcase for above described
:(mis)behaviour:
It's a bug, one that I've brought up with Kirk. The problem is that the
structures used internally by softupdates are not condusive to doing a
hard-sync. This creates other problems, too -- when the kernel
bawrite()'s a buffer softupdates may write something different to the
disk and then re-dirty the buffer, so performance will drop if the
buffer cache becomes saturated and you are doing a lot of ops that
require softupdates-related buffer rewriting. Kirk has been looking for
a solution.
-Matt
Matthew Dillon
<dillon@backplane.com>
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