On Sun, 2005-04-03 at 09:10 +0200, Manfred Spraul wrote: > Yes - sem or spin locks are quicker as long as no cache line transfers > are necessary. If the semaphore is accessed by multiple cpus, then > kmalloc would be faster: slab tries hard to avoid taking global locks. > I'm not speaking about contention, just the cache line ping pong for > acquiring a free semaphore.
Without contention, is there still a problem with cache line ping pong of acquiring a free semaphore? I mean, say only one task is using a given semaphore. Is there still going to be cache line transfers for acquiring it? Even if the task in question stays on a CPU. Is the "LOCK" on an instruction that expensive even if the other CPUs haven't accessed that location of memory. Sorry for my ignorance, I don't know all the interworkings of the Cache on SMP systems. Is there any good references on the Internet? I definitely want to know so that my coding practices for SMP improve. Thanks, -- Steve - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
