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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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| .. | ||
| skas | ||
| tt | ||
| asm-offsets.c | ||
| config.c.in | ||
| dyn.lds.S | ||
| exec_kern.c | ||
| exitcode.c | ||
| gmon_syms.c | ||
| gprof_syms.c | ||
| helper.c | ||
| init_task.c | ||
| initrd.c | ||
| irq_user.c | ||
| irq.c | ||
| ksyms.c | ||
| main.c | ||
| Makefile | ||
| mem.c | ||
| physmem.c | ||
| process_kern.c | ||
| ptrace.c | ||
| reboot.c | ||
| resource.c | ||
| sigio_kern.c | ||
| sigio_user.c | ||
| signal_kern.c | ||
| signal_user.c | ||
| smp.c | ||
| syscall_kern.c | ||
| syscall.c | ||
| sysrq.c | ||
| time_kern.c | ||
| time.c | ||
| tlb.c | ||
| trap_kern.c | ||
| trap_user.c | ||
| tty_log.c | ||
| uaccess_user.c | ||
| um_arch.c | ||
| umid.c | ||
| uml.lds.S | ||
| user_util.c | ||
| vmlinux.lds.S | ||