2 Commits

Author	SHA1	Message	Date
Christoph Lameter	f521089158	[IA64] Spinlock optimizations ... 1. Nontemporal store for spin unlock. A nontemporal store will not update the LRU setting for the cacheline. The cacheline with the lock may therefore be evicted faster from the cpu caches. Doing so may be useful since it increases the chance that the exclusive cache line has been evicted when another cpu is trying to acquire the lock. The time between dropping and reacquiring a lock on the same cpu is typically very small so the danger of the cacheline being evicted is negligible. 2. Avoid semaphore operation in write_unlock and use nontemporal store write_lock uses a cmpxchg like the regular spin_lock but write_unlock uses clear_bit which requires a load and then a loop over a cmpxchg. The following patch makes write_unlock simply use a nontemporal store to clear the highest 8 bits. We will then still have the lower 3 bytes (24 bits) left to count the readers. Doing the byte store will reduce the number of possible readers from 2^31 to 2^24 = 16 million. These patches were discussed already: http://marc.theaimsgroup.com/?t=111472054400001&r=1&w=2 http://marc.theaimsgroup.com/?l=linux-ia64&m=111401837707849&w=2 The nontemporal stores will only work using GCC. If a compiler is used that does not support inline asm then fallback C code is used. This will preserve the byte store but not be able to do the nontemporal stores. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Tony Luck <tony.luck@intel.com>	2005-08-10 16:13:10 -07:00
Linus Torvalds	1da177e4c3	Linux-2.6.12-rc2 ... Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!	2005-04-16 15:20:36 -07:00