lkml.org 
[lkml]   [2008]   [Nov]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [Bug #11308] tbench regression on each kernel release from 2.6.22 -> 2.6.28
    From
    From: Linus Torvalds <torvalds@linux-foundation.org>
    Date: Mon, 17 Nov 2008 12:30:00 -0800 (PST)

    > On Mon, 17 Nov 2008, David Miller wrote:
    > >
    > > It's on my workstation which is a much simpler 2 processor
    > > UltraSPARC-IIIi (1.5Ghz) system.
    >
    > Ok. It could easily be something like a cache footprint issue. And while I
    > don't know my sparc cpu's very well, I think the Ultrasparc-IIIi is super-
    > scalar but does no out-of-order and speculation, no?

    I does only very simple speculation, but you're description is accurate.

    > So I could easily see that the indirect branches in the scheduler
    > hurt much more, and might explain why the x86 profile looks so
    > different.

    Right.

    > One thing that non-NMI profiles also tend to show is "clumping", which in
    > turn tends to rather excessively pinpoint code sequences that release the
    > irq flag - just because those points show up in profiles, rather than
    > being a spread-out-mush. So it's possible that Ingo's profile did show the
    > scheduler more, but it was in the form of much more spread out "noise"
    > rather than the single spike you saw.

    Sure.


    \
     
     \ /
      Last update: 2008-11-17 22:01    [W:3.482 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site