Re: x86: clean up rwsem type system

From: H. Peter Anvin
Date: Thu Jan 14 2010 - 02:03:33 EST

On 01/12/2010 06:16 PM, Linus Torvalds wrote:
> In case anybody wants to test, the final piece is appended.
> Again, note the 32767-thread limit here. So this really does need that
> whole "make rwsem_count_t be 64-bit and fix the BIAS values to match"
> extension on top of it, but that is conceptually a totally independent
> issue.
> NOT TESTED! The original patch that this all was based on were tested by
> KAMEZAWA Hiroyuki, but maybe I screwed up something when I created the
> cleaned-up series, so caveat emptor..
> Also note that it _may_ be a good idea to mark some more registers
> clobbered on x86-64 in the inline asms instead of saving/restoring them.
> They are inline functions, but they are only used in places where there
> are not a lot of live registers _anyway_, so doing for example the
> clobbers of %r8-%r11 in the asm wouldn't make the fast-path code any
> worse, and would make the slow-path code smaller.

Hi Linus,

I have put these into a separate topic branch in the tip tree, which
should get them some test coverage. I will look at 64-bit counters to
support 2^31 threads hopefully later this week, unless you prefer to do
it yourself.


H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

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