On Tue, Apr 12 2005, Nick Piggin wrote:
Actually the patches I have sent you do fix real bugs, but they also
make the block layer less likely to recurse into page reclaim, so it
may be eg. hiding the problem that Neil's patch fixes.
Jens Axboe wrote on Tuesday, April 12, 2005 12:08 AM
Can you push those to Andrew? I'm quite happy with the way they turned
out. It would be nice if Ken would bench 2.6.12-rc2 with and without
those patches.
I like the patch a lot and already did bench it on our db setup. However,
I'm seeing a negative regression compare to a very very crappy patch (see
attached, you can laugh at me for doing things like that :-).
My first reaction is that the overhead is in wait queue setup and tear down
in get_request_wait function. Throwing the following patch on top does improve
things a bit, but we are still in the negative territory. I can't explain why.
Everything suppose to be faster. So I'm staring at the execution profile at
the moment.