Messages in this thread | | | From | "H. Peter Anvin" <> | Subject | Re: Intel P6 vs P7 system call performance | Date | 9 Dec 2002 11:46:47 -0800 |
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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
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