Messages in this thread | | | Date | Mon, 16 Dec 2002 12:17:59 +0100 | From | Pavel Machek <> | Subject | Re: Intel P6 vs P7 system call performance |
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Hi!
> >> Have apps enter kernel mode via Intel's purposely undefined > >> instruction, plus a few bytes of padding and identification. > >> Require that this not cross a page boundry. When it faults, > >> write the SYSENTER, INT 0x80, or SYSCALL as needed. Leave > >> the page marked clean so it doesn't need to hit swap; if it > >> gets paged in again it gets patched again. > > > > Thats *very* dirty hack. vsyscalls seem cleaner than that. > > Sure it's dirty. It's also fast, with the only overhead being > a few NOPs that could get skipped on syscall return anyway. > Patching overhead is negligible, since it only happens when a > page is brought in fresh from the disk.
Yes but "read only" code changing under you... Should better be avoided.
> The vsyscall stuff costs you on every syscall. It's nice for
Well, the cost is basically one call. That's not *that* big cost.
Pavel -- Casualities in World Trade Center: ~3k dead inside the building, cryptography in U.S.A. and free speech in Czech Republic. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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