Date: Tue, 14 Nov 1995 10:12:35 +0100 From: Poul-Henning Kamp <phk@critter.tfs.com> To: davidg@Root.COM Cc: current@freebsd.org Message-ID: <417.816340355@critter.tfs.com> In-Reply-To: Your message of "Tue, 14 Nov 1995 01:08:06 PST." <199511140908.BAA00238@corbin.Root.COM>
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> >> > 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 ?
>
> Perhaps not.
>
> >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...
>
> Umm, this isn't desired - you'll lose the ability to do write clustering.
> The scheme I implemented did buffer aging.
Hmm, that would make a difference I guess...
Well, I'll make some experiemnts with it again, some time... :-)
--
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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