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Re: how to counteract slowdown



On Wed, Nov 14, 2001 at 12:55:50PM +1100, Daniel Pittman wrote:
> How about a model like this:
> 
> When the journal hits 25% used, start async write-out.
>   -- this should also be the case for the kjournald old data. :)
> When the journal hits 75% used, start sync write-out.
> When the usage drops to 50% (or so), stop the sync write-out but
>    continue the async write-out.
> 
> That way you would hopefully see reasonable performance for short
> workloads up to 75% of the journal size.
> 
> If the write load is higher than that, the big writers get blocked
> waiting for the load to drop back down below 50%, and then are allowed
> to continue.
> 
> You would probably see a fluctuation between 50% and 75% used on long
> term heavy write loads, but short loads would be a lot smoother.
> 

Check out my thread "Journal Usage".  We're saying surprisingly similar
things at the same time on the same list...

Mike





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