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4c21e2f244
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with a many-threaded application which concurrently initializes different parts of a large anonymous area. This patch corrects that, by using a separate spinlock per page table page, to guard the page table entries in that page, instead of using the mm's single page_table_lock. (But even then, page_table_lock is still used to guard page table allocation, and anon_vma allocation.) In this implementation, the spinlock is tucked inside the struct page of the page table page: with a BUILD_BUG_ON in case it overflows - which it would in the case of 32-bit PA-RISC with spinlock debugging enabled. Splitting the lock is not quite for free: another cacheline access. Ideally, I suppose we would use split ptlock only for multi-threaded processes on multi-cpu machines; but deciding that dynamically would have its own costs. So for now enable it by config, at some number of cpus - since the Kconfig language doesn't support inequalities, let preprocessor compare that with NR_CPUS. But I don't think it's worth being user-configurable: for good testing of both split and unsplit configs, split now at 4 cpus, and perhaps change that to 8 later. There is a benefit even for singly threaded processes: kswapd can be attacking one part of the mm while another part is busy faulting. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org> |
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| abort-ev4.S | ||
| abort-ev4t.S | ||
| abort-ev5t.S | ||
| abort-ev5tj.S | ||
| abort-ev6.S | ||
| abort-lv4t.S | ||
| abort-macro.S | ||
| alignment.c | ||
| blockops.c | ||
| cache-v3.S | ||
| cache-v4.S | ||
| cache-v4wb.S | ||
| cache-v4wt.S | ||
| cache-v6.S | ||
| consistent.c | ||
| copypage-v3.S | ||
| copypage-v4mc.c | ||
| copypage-v4wb.S | ||
| copypage-v4wt.S | ||
| copypage-v6.c | ||
| copypage-xscale.c | ||
| discontig.c | ||
| extable.c | ||
| fault-armv.c | ||
| fault.c | ||
| fault.h | ||
| flush.c | ||
| init.c | ||
| ioremap.c | ||
| Kconfig | ||
| Makefile | ||
| mm-armv.c | ||
| mmap.c | ||
| mmu.c | ||
| proc-arm6_7.S | ||
| proc-arm720.S | ||
| proc-arm920.S | ||
| proc-arm922.S | ||
| proc-arm925.S | ||
| proc-arm926.S | ||
| proc-arm1020.S | ||
| proc-arm1020e.S | ||
| proc-arm1022.S | ||
| proc-arm1026.S | ||
| proc-macros.S | ||
| proc-sa110.S | ||
| proc-sa1100.S | ||
| proc-syms.c | ||
| proc-v6.S | ||
| proc-xscale.S | ||
| tlb-v3.S | ||
| tlb-v4.S | ||
| tlb-v4wb.S | ||
| tlb-v4wbi.S | ||
| tlb-v6.S | ||