Messages in this thread | | | Date | Mon, 19 Nov 2007 18:17:20 -0800 (PST) | Subject | Re: [rfc 37/45] x86_64: Support for fast per cpu operations | From | David Miller <> |
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From: "H. Peter Anvin" <hpa@zytor.com> Date: Mon, 19 Nov 2007 18:00:23 -0800
> Christoph Lameter wrote: > > Support fast cpu ops in x86_64 by providing a series of functions that > > generate the proper instructions. Define CONFIG_FAST_CPU_OPS so that core code > > can exploit the availability of fast per cpu operations. > > > > Signed-off-by: Christoph Lameter <clameter@sgi.com> > > There was, at some point, discussion about using the gcc TLS mechanism, > which should permit even better code to be generated. Unfortunately, it > would require gcc to be able to reference %gs instead of %fs (and vice > versa for i386), which I don't think is available in anything except > maybe the most cutting-edge version of gcc.
You can't use __thread because GCC will cache __thread computed addresses across context switches and cpu changes.
It's been tried before on powerpc, it doesn't work. - 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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