Messages in this thread |  | | Date | Sat, 04 Jan 2003 19:54:15 -0800 | From | Andrew Morton <> | Subject | Re: [BENCHMARK] Lmbench 2.5.54-mm2 (impressive improvements) |
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Linus Torvalds wrote: > > On Sat, 4 Jan 2003, Andrew Morton wrote: > > > > Looks like you're right. The indications are that this change > > has slowed context switches by ~5% on a PIII. The backout patch > > against 2.5.54 is below. Testing on a P4 would be useful. > > Hmm.. The backup patch doesn't handle single-stepping correctly: the > eflags cleanup singlestep patch later in the sysenter sequence _depends_ > on the stack (and thus thread) being right on the very first in-kernel > instruction.
Well that's just a straight `patch -R' of the patch which added the wrmsr's.
> That (along with benchmarking of system call numbers - the stack switch at > system call run-time ends up being quite expensive on a P4) was what made > me decide to do the traditional "write MSR in schedule" approach, even > though I agree that it would be much nicer to not have to rewrite that > stupid MSR all the time. > > It doesn't show up on lmbench (insufficient precision), but your AIM9 > numbers are quite interesting. Are they stable? >
Seem to be, but more work is needed, including oprofiling. Andi is doing some P4 testing at present. - 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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