[PATCH] uml: TLB operation batching

This adds VM op batching to skas0.  Rather than having a context switch to and
from the userspace stub for each address space change, we write a number of
operations to the stub data page and invoke a different stub which loops over
them and executes them all in one go.

The operations are stored as [ system call number, arg1, arg2, ... ] tuples.

The set is terminated by a system call number of 0.  Single operations, i.e.
page faults, are handled in the old way, since that is slightly more
efficient.

For a kernel build, a minority (~1/4) of the operations are part of a set.
These sets averaged ~100 in length, so for this quarter, the context switching
overhead is greatly reduced.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 18 deletions

diff --git a/arch/um/include/tlb.h b/arch/um/include/tlb.h
index c6f9628f39bf..2deefb99c63c 100644
--- a/arch/um/include/tlb.h
+++ b/arch/um/include/tlb.h
@@ -9,7 +9,7 @@
 #include "um_mmu.h"
 
 struct host_vm_op {
-        enum { MMAP, MUNMAP, MPROTECT } type;
+        enum { NONE, MMAP, MUNMAP, MPROTECT } type;
         union {
                 struct {
                         unsigned long addr;
@@ -38,24 +38,10 @@ extern void mprotect_kernel_vm(int w);
 extern void force_flush_all(void);
 extern void fix_range_common(struct mm_struct *mm, unsigned long start_addr,
                              unsigned long end_addr, int force,
-                             void (*do_ops)(union mm_context *,
-                                            struct host_vm_op *, int));
+                             void *(*do_ops)(union mm_context *,
+                                             struct host_vm_op *, int, int,
+                                             void *));
 extern int flush_tlb_kernel_range_common(unsigned long start,
                                          unsigned long end);
 
-extern int add_mmap(unsigned long virt, unsigned long phys, unsigned long len,
-                    int r, int w, int x, struct host_vm_op *ops, int index,
-                    int last_filled, union mm_context *mmu,
-                    void (*do_ops)(union mm_context *, struct host_vm_op *,
-                                   int));
-extern int add_munmap(unsigned long addr, unsigned long len,
-                      struct host_vm_op *ops, int index, int last_filled,
-                      union mm_context *mmu,
-                      void (*do_ops)(union mm_context *, struct host_vm_op *,
-                                     int));
-extern int add_mprotect(unsigned long addr, unsigned long len, int r, int w,
-                        int x, struct host_vm_op *ops, int index,
-                        int last_filled, union mm_context *mmu,
-                        void (*do_ops)(union mm_context *, struct host_vm_op *,
-                                       int));
 #endif