Messages in this thread | | | Date | Thu, 21 Oct 2010 14:17:01 +0800 | From | Shaohua Li <> | Subject | Re: [tip:x86/mm] percpu: Introduce a read-mostly percpu API |
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On Thu, Oct 21, 2010 at 02:09:47PM +0800, H. Peter Anvin wrote: > On 10/20/2010 11:07 PM, Eric Dumazet wrote: > > Le mercredi 20 octobre 2010 à 22:54 -0700, H. Peter Anvin a écrit : > > > >> L1_CACHE_BYTES is completely pointless, since if there is sharing to > >> worry about *at all*, it's probably at the L2 or L3 cache levels. > >> > > > > I see, and we dont have better way to express this hint/requirement than > > using PAGE_SIZE or INTERNODE_CACHE_SHIFT ? > > > > In your patch you force a PAGE_SIZE alignement *before* > > *(.data..percpu..page_aligned) > > > > If this alignment is really needed, this should be part of another > > patch, since this fixes a previous bug in 2.6.36 ? > > > > It was part of Shaohua's patch... I don't know if it does anything > useful, but it also doesn't hurt. This isn't a previous bug. see #define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \ DECLARE_PER_CPU_SECTION(type, name, "..page_aligned") \ __aligned(PAGE_SIZE) the ..page_aligned is already page aligned. I add it is because it can make the .readmostly section guarantee to have no cache false sharing, because I add the . = ALIGN(PAGE_SIZE); before .readmostly section, and .page_aligned follows, but for sure this wates some memory. -- 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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