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Re: pagebuf_prepare_write doesn't kmap the page

To: Marcelo Tosatti <marcelo@xxxxxxxxxxxxxxxx>, linux-xfs@xxxxxxxxxxx
Subject: Re: pagebuf_prepare_write doesn't kmap the page
From: Steve Lord <lord@xxxxxxx>
Date: Wed, 31 Jan 2001 10:43:42 -0600
In-reply-to: Message from Steve Lord <lord@xxxxxxx> of "Wed, 31 Jan 2001 10:37:05 CST." <200101311637.f0VGb5n26720@xxxxxxxxxxxxxxxxxxxx>
Sender: owner-linux-xfs@xxxxxxxxxxx
To follow up on my own message - running some micro benchmarks, every single
individual operation got faster, but dbench got slower.....

Ho Hum.

Steve


> > 
> > On Wed, 31 Jan 2001, Steve Lord wrote:
> > 
> > > 
> > > OK, I see what is going on here - and I think this could actually
> > > break regular XFS as well - if you use the loop device on a highmem
> > > machine. I will fix it in my 2.4.1 merge which should be out in cvs
> > > in a day or two. 2.4.1 is running with XFS, but I am not happy with
> > > what the kernel changes have done to performance.
> > 
> > Steve, 
> > 
> > Could you please describe what performance problems are going on? 
> > 
> 
> 
> It is difficult to nail down the cause yet, but dbench has taken a
> significant hit (40%). Single file (bonnie) is comparable with 2.4.0, the
> dbench issue may be related to the throttling being placed on the
> ll_rw_block interface by Jens' changes. The problem with working out
> a bottleneck in dbench is it is such a random pile of stuff that
> you really cannot point a finger at any one thing. I need to go
> find some more deterministic measurements.
> 
> The performance drop off is not limited to xfs though ext2 appears
> to suffer as well.
> 
> Steve
> 



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