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From: Andi Kleen <ak@suse.de>
To: Jimi Xenidis <jimix@watson.ibm.com>
Cc: rusty@rustcorp.com.au, xen-devel@lists.xensource.com
Subject: Re: My turn to rant about types... bitops
Date: 06 Oct 2005 15:39:53 +0200	[thread overview]
Message-ID: <p73achmzrva.fsf@verdi.suse.de> (raw)
In-Reply-To: <FFC5FB0D-2386-4617-827A-4153E331586A@watson.ibm.com>

Jimi Xenidis <jimix@watson.ibm.com> writes:
> 
> The next request is really the jist of what we are after, doing 64bit
> operations 32bit aligned data kills us performance wise and WRT
> bitops cannot be used for atomic ops. If htis was just Xen I'd
> consider adding 32bit bitops but I doubt I'd be able to do that in
> Linux which does not provide "u32" bitops.

Actually it does - when the arch has ARCH_HAS_ATOMIC_UNSIGNED set
it's allowed with the normal bitops.
 
> IIRC assuring this alignement would even help x86, no?

I doubt it (unless you're straddling a cache line) 

-Andi

  reply	other threads:[~2005-10-06 13:39 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-10-05 16:52 My turn to rant about types... bitops Jimi Xenidis
2005-10-05 18:17 ` Keir Fraser
2005-10-06 11:32   ` Jimi Xenidis
2005-10-06 13:39     ` Andi Kleen [this message]
2005-10-06 15:10       ` Jimi Xenidis
2005-10-06 15:19         ` Andi Kleen
     [not found]   ` <7D88E873-B404-4E28-BE87-D474F67CAA82@watson.ibm.com>
2005-10-06 12:49     ` Keir Fraser
2005-10-10 11:44   ` Rusty Russell

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