Messages in this thread |  | | | Date | Tue, 6 Apr 2004 17:59:25 +0200 | | From | Andrea Arcangeli <> | | Subject | Re: -mmX 4G patches feedback [numbers: how much performance impact] |
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On Tue, Apr 06, 2004 at 01:55:39PM +0200, Ingo Molnar wrote: > > http://redhat.com/~mingo/4g-patches/loop_print.c
loop print does no memory access at all, it just loops forever, no surprise at all you get very little slowdown no matter how many tlb flushes happens.
If people needs >3G of user address space I assume they do some bulk memory access too in their application.
Please write a realistic benchmark and repeat the test, the numbers you posted are totally meaningless. Try a kernel compile of something actually realistic (and a kernel compile doing lots of execve isn't the worst case either).
Also note that the slowdown for app calling heavily syscalls is 30% not 5-10%, no matter if they're threaded or not, further more there has been no proof that the 30% slowdown of mysql is really related to the copy-users being serialized by a thread-wide spinlock, we made that assumption but it's not certain yet.
You should also use a bleeding edge cpu for you measurements with large tlb caches, which cpu did you use for your measurements? - 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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