Messages in this thread |  | | | Subject | Re: Maybe a VM bug in 2.4.18-18 from RH 8.0? | | From | Arjan van de Ven <> | | Date | 07 Dec 2002 11:55:46 +0100 |
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On Sat, 2002-12-07 at 01:01, Andrew Morton wrote: > William Lee Irwin III wrote: > > > > ... > > A 16KB or 64KB kernel allocation unit would then annihilate > > You want to be careful about this: > > CPU: L1 I cache: 16K, L1 D cache: 16K > > Because instantiating a 16k page into user pagetables in > one hit means that it must all be zeroed. With these large > pagesizes that means that the application is likely to get > 100% L1 misses against the new page, whereas it currently > gets 100% hits.
If you really want you can cheat that 100% statistic into something much lower by zeroing the page from back to front (based on the exact faulting address even, because you know THAT one will get used) and/or zeroing the second half while bypassing the cache. At least it's 50% hits then ;)
Still not 100% and I still agree that the 8Kb number is much nicer for 16Kb L1 cache machines.... - 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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