Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [rfc 37/45] x86_64: Support for fast per cpu operations | Date | Tue, 20 Nov 2007 04:23:07 +0100 |
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On Tuesday 20 November 2007 03:19, H. Peter Anvin wrote: > David Miller wrote: > >> 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. > > OK, that pretty much answers that question.
I investigated that some time ago.
There are other obstacles too on x86-64, e.g. the relocations are wrong for kernel mode. You would need to extend the linker first.
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