tlb_gather_mmu dates from before kernel preemption was allowed, and uses
smp_processor_id or __get_cpu_var to find its per-cpu mmu_gather.  That works
because it's currently only called after getting page_table_lock, which is not
dropped until after the matching tlb_finish_mmu.  But don't rely on that, it
will soon change: now disable preemption internally by proper get_cpu_var in
tlb_gather_mmu, put_cpu_var in tlb_finish_mmu.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The generic TLB flush functions kept upto 506 pages per
CPU to avoid too frequent IPIs.

This value was done for the L1 cache of older x86 CPUs,
but with modern CPUs it does not make much sense anymore.
TLB flushing is slow enough that using the L2 cache is fine.

This patch increases the flush array on x86-64 to cache
5350 pages. That is roughly 20MB with 4K pages. It speeds
up large munmaps in multithreaded processes on SMP considerably.

The cost is roughly 42k of memory per CPU, which is reasonable.

I only increased it on x86-64 for now, but it would probably
make sense to increase it everywhere. Embedded architectures
with SMP may keep it smaller to save some memory per CPU.
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

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!