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Date:      Mon, 10 Feb 2003 04:00:00 -0800
From:      Terry Lambert <tlambert2@mindspring.com>
To:        phk@phk.freebsd.dk
Cc:        David Schultz <dschultz@uclink.Berkeley.EDU>, arch@FreeBSD.ORG
Subject:   Re: Our lemming-syncer caught in the act.
Message-ID:  <3E479440.D89E90F5@mindspring.com>
References:  <37473.1044868995@critter.freebsd.dk>

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phk@phk.freebsd.dk wrote:
> In message <20030210091317.GD5165@HAL9000.homeunix.com>, David Schultz writes:
> >When a large file times out, a significant amount of I/O can be
> >generated.  This is still far better than the old syncer that
> >flushed everything every 30 seconds.  The reasons for this
> >behavior are explained in src/sys/ufs/ffs/README.  After reading
> >that, do you still think it makes sense to try to do better?
> 
> Yes, it makes a lot of sense.  There is no point in batching up
> writes to the point of showing 200 requests off at once then
> wait 30 seconds, then do it again etc etc.
> 
> We can and need to do better than that.

Are there any statistics on how many requests are prevented by
soft updates?  Maybe you are really talking about a value that
would be best expressed as a ratio?

It seems to me that this would be a necessary part of any changes
made on the basis of instrumentation that might decrease the
interval, but increase the absolute number of requests, as a
result.

-- Terry

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