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    SubjectRe: Intel P6 vs P7 system call performance
    Date
    Followup to:  <20021209193649.GC10316@suse.de>
    By author: Dave Jones <davej@codemonkey.org.uk>
    In newsgroup: linux.dev.kernel
    >
    > On Mon, Dec 09, 2002 at 05:48:45PM +0000, Linus Torvalds wrote:
    >
    > > P4's really suck at system calls. A 2.8GHz P4 does a simple system call
    > > a lot _slower_ than a 500MHz PIII.
    > >
    > > The P4 has problems with some other things too, but the "int + iret"
    > > instruction combination is absolutely the worst I've seen. A 1.2GHz
    > > Athlon will be 5-10 times faster than the fastest P4 on system call
    > > overhead.
    >
    > Time to look into an alternative like SYSCALL perhaps ?
    >

    SYSCALL is AMD. SYSENTER is Intel, and is likely to be significantly
    faster. Unfortunately SYSENTER is also extremely braindamaged, in
    that it destroys *both* the EIP and the ESP beyond recovery, and
    because it's allowed in V86 and 16-bit modes (where it will cause
    permanent data loss) which means that it needs to be able to be turned
    off for things like DOSEMU and WINE to work correctly.

    -hpa

    --
    <hpa@transmeta.com> at work, <hpa@zytor.com> in private!
    "Unix gives you enough rope to shoot yourself in the foot."
    http://www.zytor.com/~hpa/puzzle.txt <amsp@zytor.com>
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