Re: [PATCH 00/23] per device dirty throttling -v8

On Sat, 4 Aug 2007, Ingo Molnar wrote:

i forgot this entry:

 " We recently upgraded our office to gigabit Ethernet and got some big 
   AMD64 / 3ware boxes for file and vmware servers... only to find them 
   almost useless under any kind of real load. I've built some patched 
   2.6.21.6 kernels (using the bdi throttling patch you mentioned) to 
   see if our various Debian Etch boxes run better. So far my testing 
   shows a *great* improvement over the stock Debian 2.6.18 kernel on 
   our configurations. "

Well, quite frankly, there are other changes between 2.6.18 and 2.6.21 
that are more likely to be a big deal than Peter's patches. No offense to 
Peter, but we also cut the default dirty percentage by a factor of four in 
that timeframe, and that made a *huge* difference for some setups (and 
admittedly not so much on others ;)

and bdi has been in -mm in the past i think, so we also know (to a 
certain degree) that it does not hurt those workloads that are fine 
either.

Hey, I'm not complaining. I think the code looks fine. I just want to make 
sure that it actually helps.

[ my personal interest in this is the following regression: every time i
  start a large kernel build with DEBUG_INFO on a quad-core 4GB RAM box,
  i get up to 30 seconds complete pauses in Vim (and most other tasks),
  during plain editing of the source code. (which happens when Vim tries
  to write() to its swap/undo-file.) ]

So do the patches really end up helping your case? Or is this just why 
you're following it, and hoping they'll eventually do so?

		Linus

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