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    SubjectRe: Time sliced CFQ io scheduler
    FromNick Piggin <>
    DateWed, 08 Dec 2004 18:19:49 +1100
    On Wed, 2004-12-08 at 08:11 +0100, Jens Axboe wrote:
    > On Wed, Dec 08 2004, Nick Piggin wrote:
    > > On Wed, 2004-12-08 at 07:55 +0100, Jens Axboe wrote:
    
    > > > Currently I think the time sliced cfq is the best all around. There's
    > > > still a few kinks to be shaken out, but generally I think the concept is
    > > > sounder than AS.
    > > > 
    > > 
    > > But aren't you basically unconditionally allowing a 4ms idle time after
    > > reads? The complexity of AS (other than all the work we had to do to get
    > > the block layer to cope with it), is getting it to turn off at (mostly)
    > > the right times. Other than that, it is basically the deadline
    > > scheduler.
    > 
    > Yes, the concept is similar and there will be time wasting currently.
    > I've got some cases covered that AS doesn't, and there are definitely
    > some the other way around as well.
    > 
    
    Oh? What have you got covered that AS doesn't? (I'm only reading the
    patch itself, which isn't trivial to follow).
    
    > If you have any test cases/programs, I'd like to see them.
    > 
    
    Hmm, damn. Lots of stuff. I guess some of the notable ones that I've
    had trouble with are OraSim (Oracle might give you a copy), Andrew's
    patch scripts when applying a stack of patches, pgbench... can't
    really remember any others off the top of my head.
    
    I've got a small set of basic test programs that are similar to the
    sort of tests you've been running in this thread as well.
    
    
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