Messages in this thread |  | | Date | Mon, 10 Feb 2014 22:14:58 +0100 | From | Peter Zijlstra <> | Subject | Re: [RFC][PATCH 0/5] arch: atomic rework |
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On Mon, Feb 10, 2014 at 04:08:11PM -0500, Chris Metcalf wrote: > (+LKML again) > > On 2/10/2014 3:57 PM, Peter Zijlstra wrote: > > On Mon, Feb 10, 2014 at 03:50:04PM -0500, Chris Metcalf wrote: > >> On 2/6/2014 8:52 AM, Peter Zijlstra wrote: > >>> Its been compiled on everything I have a compiler for, however frv and > >>> tile are missing because they're special and I was tired. > >> So what's the specialness on tile? > > Its not doing the atomic work in ASM but uses magic builtins or such. > > > > I got the list of magic funcs for tilegx, but didn't look into the 32bit > > chips. > > Oh, I see. The <asm/atomic.h> files on tile are already reasonably well-factored. > > It's possible you could do better, but I think not by too much, other than possibly > by using <asm-generic/atomic.h> for some of the common idioms like "subtraction > is addition with a negative second argument", etc., which hasn't been done elsewhere.
The last patch 5/5 adds a few atomic ops; I could of course use cmpxchg() loops for everything, but I found tilegx actually has fetch_or and fetch_and to implement atomic_or() / atomic_and().
It doesn't have fetch_xor() from what I've been told so atomic_xor() will have to become a cmpxchg() loop.
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