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    SubjectRe: [Bug #11308] tbench regression on each kernel release from 2.6.22 -> 2.6.28
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    On Mon, 2008-09-15 at 12:44 +0200, Mike Galbraith wrote:
    > On Sun, 2008-09-14 at 21:51 +0200, Mike Galbraith wrote:
    > > On Sun, 2008-09-14 at 09:18 -0500, Christoph Lameter wrote:
    > > > Mike Galbraith wrote:
    > > > > Numbers from my Q6600 Aldi supermarket box (hm, your box is from different shelf)
    > > > >
    > > > My box is an 8p with recent quad core processors. 8G, 32bit Linux.
    > >
    > > Don't hold your breath, but after putting my network config of a very
    > > severe diet, I'm starting to see something resembling sensible results.
    >
    > Turns off all netfilter options except tables, etc.
    >
    > Since 2.6.22.19-cfs-v24.1 and 2.6.23.17-cfs-v24.1 schedulers are
    > identical, and these are essentially identical with 2.6.24.7, what I
    > read from numbers below is that cfs in 2.6.23 was somewhat less than
    > wonderful for either netperf or tbench, Something happened somewhere
    > other than the scheduler at 23->24 which cost us some performance, and
    > another something happened at 26->27. I'll likely go looking again..
    > and likely regret it again ;-)

    Bisecting 26->27 yet again turned up a repeatable downturn in netperf
    throughput. There is no difference at this point with tbench.

    Bisect says first bad commit is 847106f, a security merge. Post
    bisection sanity checkouts say...

    v2.6.26-21-g2069f45
    16384 87380 1 1 60.00 98435.13
    16384 87380 1 1 60.01 99259.90
    16384 87380 1 1 60.01 99325.61
    16384 87380 1 1 60.00 99039.84

    v2.6.26-343-g847106f
    16384 87380 1 1 60.00 94764.59
    16384 87380 1 1 60.00 94909.89
    16384 87380 1 1 60.00 94858.63
    16384 87380 1 1 60.00 94801.12

    ...every time. I knew I'd regret doing this.

    -Mike



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