RE: [Xen-devel] [patch] bitops on irq_cpustat_t->__softirq_pending

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: Hollis Blanchard
>Sent: 2006年3月31日 0:45
>Instead, this patch changes asm-x86/hardirq.h to use a long where PPC
>needs
>it. This doesn't change the size of the structure for x86. There are other
>ways we could and should do this code-sharing, but this one is the least
>impact (and this is an area where IA64's divergence is potentially
>problematic).

Xen/IA64 has percpu hardware pages support and so softirq pending 
indicator is put together with other more percpu stuffs placed on the 
percpu pages. That can accelerate percpu access a lot. 

Another concern is, IA64 supports atomic bitops with different width, just 
like x86 while long is double size of integer on IA64. If the similar 
approach in this patch is used in other common places, it will add 
unnecessary size to xen/ia64. 

Thanks,
Kevin

>
>I think it would be a good idea to make a wiki page that covers the files
>that
>are candidates for sharing. I know Jimi has investigated this subject...
>

Agree.

Thanks,
Kevin

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