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Re: how to counteract slowdown


--On Tuesday, November 13, 2001 09:04:19 PM -0800 Andrew Morton <akpm zip com au> wrote:

oops.  When a transaction reaches 25% of the journal size,
we force a commit.

When the journal is 50% to 75% full, we force a checkpoint (that is,
write buffers from earlier transactions out so we can release the
journal space).

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.

It's sort-of like that now. At 50%-70% occupancy we do a synchronous checkpoint.

I'm not sure I get what you mean. Does this mean that there are sync writes until the journal is empty or until it is less then 50% full?

I'm still puzzeled that sync writes would make a machine completely unusable for 30 seconds.


from the desk of Patrick C. F. Ernzer
Red Hat Europe

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