Messages in this thread | | | Date | Fri, 08 Feb 2002 15:04:34 -0500 | From | Jeff Garzik <> | Subject | Re: [RFC] New locking primitive for 2.5 |
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Linus Torvalds wrote: > > On Fri, 8 Feb 2002, Ingo Molnar wrote: > > > > and regarding the reintroduction of BKL, *please* do not just use a global > > locks around such pieces of code, lock bouncing sucks on SMP, even if > > there is no overhead. > > I'd suggest not having a lock at all, but instead add two functions: one > to read a 64-bit value atomically, the other to write it atomically (and > they'd be atomic only wrt each other, no memory barriers etc implied). > > On 64-bit architectures that's just a direct dereference, and even on x86 > it's just a "cmpxchg8b".
Are there architectures out there that absolutely must implement this with a spinlock? Your suggested API of functions to read/write 64-bit values atomically would work for such a case, but still I am just curious.
Jeff
-- Jeff Garzik | "I went through my candy like hot oatmeal Building 1024 | through an internally-buttered weasel." MandrakeSoft | - goats.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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