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Re: how to counteract slowdown



On Tue, 13 Nov 2001, Mike Fedyk wrote:
> 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...

I noted that after sending the mail, but didn't want to say more unless
I could contribute something of value.

As it is, I don't have /much/ to say except that I am going to see if I
can find time to look at producing something workable to test this sort
of implementation -- unless one of the people who know the code want to
say that they are?

        Daniel

-- 
We watched with envy on television as American solders gave out packets of
Marlboro cigarettes to Iraqi prisoners of war. May of us have to work an
entire shift underground to afford one packet of Marlboros. I want to
surrender to the Americans.
        -- Sergei Yevshin, a coal miner on strike in the Ukraine





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