Re: separating out memory checks from INVARIANTS
- From: Bruce Evans <brde@xxxxxxxxxxxxxxx>
- Date: Mon, 17 Mar 2008 00:45:12 +1100 (EST)
On Sat, 15 Mar 2008, Jeff Roberson wrote:
On Sat, 15 Mar 2008, Kip Macy wrote:Would it make it possible to do memory allocation without holding a
lock in the M_NOWAIT case?
Yes, when I originally wrote the code it didn't require a lock because I relied on byte writes being atomic. However, we had platforms for which that wasn't true. (alpha). It may be that it's safe not to lock even now on x86/amd64. I don't know the specifics of the memory architectures on powerpc, arm, mips, etc. though.
sparc64 only supports atomic ops on sizes 32 and 64 bits. I think it
and not alpha was responsible for eliminating use of 8 and 16 bit
atomic ops in MI code.
My version of atomic.h for i386 only supports atomic ops on size 32.
8 and 16 bit atomic ops are not usable in MI code and are or were not
used in i386 MD code, so they are just interface bloat.
Bruce
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