Re: Fwd: 5-STABLE kernel build with icc broken

From: jason henson (jason_at_ec.rr.com)
Date: 03/30/05

  • Next message: Peter Pentchev: "Re: ABV.BG автоматичен отговор" 
    Date: Tue, 29 Mar 2005 22:57:28 -0500
To: Peter Jeremy <PeterJeremy@optushome.com.au>

    Peter Jeremy wrote:

    >On Mon, 2005-Mar-28 23:23:19 -0800, David Leimbach wrote:
    >
    >
    >>meant to send this to the list too... sorry
    >>
    >>
    >>>Are you implying DragonFly uses FPU/SIMD? For that matter does any kernel?
    >>>
    >>>
    >>I believe it does use SIMD for some of it's fast memcopy stuff for
    >>it's messaging system
    >>actually. I remember Matt saying he was working on it.
    >>
    >>http://leaf.dragonflybsd.org/mailarchive/kernel/2004-04/msg00262.html
    >>
    >>
    >
    >That's almost a year ago and specifically for the amd64. Does anyone
    >know what the results were?
    >
    >
    >
    >>If you can manage the alignment issues it can be a huge win.
    >>
    >>
    >
    >For message passing within the kernel, you should be able to mandate
    >alignment as part of the API.
    >
    >I see the bigger issue being the need to save/restore the SIMD
    >engine's state during a system call. Currently, this is only saved on
    >if a different process wants to use the SIMD engine. For MMX, the
    >SIMD state is the FPU state - which is non-trivial. The little
    >reading I've done suggests that SSE and SSE2 are even larger.
    >
    >Saving the SIMD state would be more expensive that using integer
    >registers for small (and probably medium-sized) copies.
    >
    >
    >
    Later in that thread they discuss skipping the restore state to make
    things faster. The minimum buffer size they say this will be good for
    is between 2-4k. Does this make sense, or am I showing my ignorance?

    http://leaf.dragonflybsd.org/mailarchive/kernel/2004-04/msg00264.html
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  • Next message: Peter Pentchev: "Re: ABV.BG автоматичен отговор"

    Relevant Pages

    • Re: Fwd: 5-STABLE kernel build with icc broken
      ... >I believe it does use SIMD for some of it's fast memcopy stuff for ... >it's messaging system ... I see the bigger issue being the need to save/restore the SIMD ... SIMD state is the FPU state - which is non-trivial. ...
      (freebsd-hackers)
    • Re: Fwd: 5-STABLE kernel build with icc broken
      ... >>it's messaging system ... I remember Matt saying he was working on it. ... I think they were related to the SIMD stuff. ... > Saving the SIMD state would be more expensive that using integer ...
      (freebsd-hackers)