[IA64] Use bitmaps for efficient context allocation/free
Corrects the very inefficent method of finding free context_ids in
get_mmu_context(). Instead of walking the task_list of all processes,
2 bitmaps are used to efficently store and lookup state, inuse and
needs flushing. The entire rid address space is now used before calling
wrap_mmu_context and global tlb flushing.
Special thanks to Ken and Rohit for their review and modifications in
using a bit flushmap.
Signed-off-by: Peter Keilty <peter.keilty@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/include/asm-ia64/mmu_context.h b/include/asm-ia64/mmu_context.h
index 8d6e72f..8d9b30b 100644
--- a/include/asm-ia64/mmu_context.h
+++ b/include/asm-ia64/mmu_context.h
@@ -32,13 +32,17 @@
struct ia64_ctx {
spinlock_t lock;
unsigned int next; /* next context number to use */
- unsigned int limit; /* next >= limit => must call wrap_mmu_context() */
- unsigned int max_ctx; /* max. context value supported by all CPUs */
+ unsigned int limit; /* available free range */
+ unsigned int max_ctx; /* max. context value supported by all CPUs */
+ /* call wrap_mmu_context when next >= max */
+ unsigned long *bitmap; /* bitmap size is max_ctx+1 */
+ unsigned long *flushmap;/* pending rid to be flushed */
};
extern struct ia64_ctx ia64_ctx;
DECLARE_PER_CPU(u8, ia64_need_tlb_flush);
+extern void mmu_context_init (void);
extern void wrap_mmu_context (struct mm_struct *mm);
static inline void
@@ -83,9 +87,16 @@
context = mm->context;
if (context == 0) {
cpus_clear(mm->cpu_vm_mask);
- if (ia64_ctx.next >= ia64_ctx.limit)
- wrap_mmu_context(mm);
+ if (ia64_ctx.next >= ia64_ctx.limit) {
+ ia64_ctx.next = find_next_zero_bit(ia64_ctx.bitmap,
+ ia64_ctx.max_ctx, ia64_ctx.next);
+ ia64_ctx.limit = find_next_bit(ia64_ctx.bitmap,
+ ia64_ctx.max_ctx, ia64_ctx.next);
+ if (ia64_ctx.next >= ia64_ctx.max_ctx)
+ wrap_mmu_context(mm);
+ }
mm->context = context = ia64_ctx.next++;
+ __set_bit(context, ia64_ctx.bitmap);
}
}
spin_unlock_irqrestore(&ia64_ctx.lock, flags);