Date: Tue, 14 Nov 1995 09:51:26 +0100 From: Poul-Henning Kamp <phk@critter.tfs.com> To: davidg@Root.COM Cc: current@freebsd.org Message-ID: <336.816339086@critter.tfs.com> In-Reply-To: Your message of "Tue, 14 Nov 1995 00:43:12 PST." <199511140843.AAA00206@corbin.Root.COM>
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> >> "Fixing" this is very difficult and would require a rewrite of the code
> >> involved.
> >
> >Why would this:
> >
> > void
> > update_every_3_sec()
> > {
> > static int i;
> >
> > for all buffers {
> > if ((blockno % 10) == i)
> > write it
> > }
> > i = ++i % 10;
> > }
> >
> >give more io traffic ?
>
> Because delayed write buffers are delayed for a reason. It's the
> expectation that additional data/changes will be made to the buffer before
> it is written out. In the case where stuff is being appended to files via
> small writes (like log files, for instance), doing an update 10 times more
> often may very well increase the number of writes by 10 times.
I still don't follow you.
Are we talking about the same thing ?
The mean time between updates for any one particular buffer is still
30 seconds, so how can this change so much ? We just stage the
writes instead of doing them all at the same time.
Unless you can show me where we prefer buffers with a particular last
decimal digit in their block-numbers then I have a hard time beliving
your results...
I had a patch (crude hack really) for this back in Pleasant Hill but I have
no idea where to find it now, but it didn't show any adverse effects for me,
quite the contrary... It cured the hangs I had, which was the kind
which would be signalled by a significant rattle from the disks...
--
Poul-Henning Kamp | phk@FreeBSD.ORG FreeBSD Core-team.
http://www.freebsd.org/~phk | phk@login.dknet.dk Private mailbox.
whois: [PHK] | phk@ref.tfs.com TRW Financial Systems, Inc.
Future will arrive by its own means, progress not so.
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