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Re: thoughts on libatomic
- From: Andrew MacLeod <amacleod at redhat dot com>
- To: Richard Henderson <rth at redhat dot com>
- Cc: Torvald Riegel <triegel at redhat dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 23 Apr 2012 16:55:38 -0400
- Subject: Re: thoughts on libatomic
- References: <email@example.com> <4F95ADAE.firstname.lastname@example.org>
On 04/23/2012 03:29 PM, Richard Henderson wrote:
yes, this keeps coming up again and again.... I think you should take
it up with Lawrence Crowl... He was the one, (along with some input from
Jeffrey Yasskin) that concluded that it was OK to use it, even if it
was just sort of shoehorned in so that we could get 16 byte lock free on
the most common architecture...
- I'm concerned about the CAS on read-only mprotected pages?
Why again do we think this is safe? Does the standard explicitly
allow this? Or should we just use a lock in this case?
Andrew, you had a bit of back-and-forth with someone about this.
Can you dig that up?
it came down to something like the architecture manual entry for
cmpxchg16 states that a store cycle may be added by the hardware under
the covers, and as such, it is a part of the basic machine description,
and therefore we might as well use the instruction even though we may be
adding the store cycle ourselves sometimes....
I haven't found the actual communication for reference yet, I'll look