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    SubjectRe: Intel P6 vs P7 system call performance
    Linus Torvalds wrote:

    > ===== arch/i386/kernel/sysenter.c 1.1 vs edited =====
    > --- 1.1/arch/i386/kernel/sysenter.c Mon Dec 16 21:39:04 2002
    > +++ edited/arch/i386/kernel/sysenter.c Tue Dec 17 11:39:39 2002
    > @@ -48,14 +48,14 @@
    > 0xc3 /* ret */
    > };
    > static const char sysent[] = {
    > - 0x55, /* push %ebp */
    > 0x51, /* push %ecx */
    > 0x52, /* push %edx */
    > + 0x55, /* push %ebp */
    > 0x89, 0xe5, /* movl %esp,%ebp */
    > 0x0f, 0x34, /* sysenter */
    > + 0x5d, /* pop %ebp */
    > 0x5a, /* pop %edx */
    > 0x59, /* pop %ecx */
    > - 0x5d, /* pop %ebp */
    > 0xc3 /* ret */

    Instead of duplicating the push/pop %ebp just use the first one by using

    movl 12(%ebo), %ebp

    in the kernel code or remove the first. The later is better, smaller code.

    --
    --------------. ,-. 444 Castro Street
    Ulrich Drepper \ ,-----------------' \ Mountain View, CA 94041 USA
    Red Hat `--' drepper at redhat.com `---------------------------

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