bitkeeper revision 1.131 (3e7270ecL24hQl_PjDBYoS8hhB8GTA)

multicall.h:
  new file
Many files:
  Multicall now available, so that Xen syscalls can be batched to amortise cost of trap to ring 0. Used by xenolinux to reduce the cost of a context switch.

3 files changed, 82 insertions, 10 deletions

diff --git a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/hypervisor.h b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/hypervisor.h
index 16f37cfe65..4b9591102c 100644
--- a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/hypervisor.h
+++ b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/hypervisor.h
@@ -129,6 +129,7 @@ static inline int flush_page_update_queue(void)
     return idx;
 }
 #define XENO_flush_page_update_queue() (_flush_page_update_queue())
+void MULTICALL_flush_page_update_queue(void);
 
 
 /*
@@ -183,14 +184,24 @@ static inline int HYPERVISOR_set_gdt(unsigned long *frame_list, int entries)
     return ret;
 }
 
-static inline int HYPERVISOR_stack_and_ldt_switch(
-    unsigned long ss, unsigned long esp, unsigned long ldts)
+static inline int HYPERVISOR_stack_switch(unsigned long ss, unsigned long esp)
 {
     int ret;
     __asm__ __volatile__ (
         TRAP_INSTR
-        : "=a" (ret) : "0" (__HYPERVISOR_stack_and_ldt_switch),
-        "b" (ss), "c" (esp), "d" (ldts) );
+        : "=a" (ret) : "0" (__HYPERVISOR_stack_switch),
+        "b" (ss), "c" (esp) : "memory" );
+
+    return ret;
+}
+
+static inline int HYPERVISOR_ldt_switch(unsigned long ldts)
+{
+    int ret;
+    __asm__ __volatile__ (
+        TRAP_INSTR
+        : "=a" (ret) : "0" (__HYPERVISOR_ldt_switch),
+        "b" (ldts) : "memory" );
 
     return ret;
 }
@@ -215,13 +226,12 @@ static inline int HYPERVISOR_fpu_taskswitch(void)
     return ret;
 }
 
-static inline int HYPERVISOR_do_sched_op(void *sched_op)
+static inline int HYPERVISOR_yield(void)
 {
     int ret;
     __asm__ __volatile__ (
         TRAP_INSTR
-        : "=a" (ret) : "0" (__HYPERVISOR_sched_op),
-        "b" (sched_op) );
+        : "=a" (ret) : "0" (__HYPERVISOR_yield) );
 
     return ret;
 }
@@ -296,7 +306,7 @@ static inline int HYPERVISOR_update_descriptor(
     int ret;
     __asm__ __volatile__ (
         TRAP_INSTR
-        : "=a" (ret) : "0" (__HYPERVISOR_set_gdt), 
+        : "=a" (ret) : "0" (__HYPERVISOR_update_descriptor), 
         "b" (pa), "c" (word1), "d" (word2) );
 
     return ret;
@@ -324,4 +334,15 @@ static inline int HYPERVISOR_dom_mem_op(void *dom_mem_op)
     return ret;
 }
 
+static inline int HYPERVISOR_multicall(void *call_list, int nr_calls)
+{
+    int ret;
+    __asm__ __volatile__ (
+        TRAP_INSTR
+        : "=a" (ret) : "0" (__HYPERVISOR_multicall),
+        "b" (call_list), "c" (nr_calls) : "memory" );
+
+    return ret;
+}
+
 #endif /* __HYPERVISOR_H__ */
diff --git a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/mmu_context.h b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/mmu_context.h
index c5b3cdcd61..ad07796f95 100644
--- a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/mmu_context.h
+++ b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/mmu_context.h
@@ -5,6 +5,7 @@
 #include <asm/desc.h>
 #include <asm/atomic.h>
 #include <asm/pgalloc.h>
+#include <asm/multicall.h>
 
 /*
  * possibly do the LDT unload here?
@@ -33,6 +34,7 @@ extern pgd_t *cur_pgd;
 
 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, struct task_struct *tsk, unsigned cpu)
 {
+	cli(); /* protect flush_update_queue multicall */
 	if (prev != next) {
 		/* stop flush ipis for the previous mm */
 		clear_bit(cpu, &prev->cpu_vm_mask);
@@ -50,7 +52,7 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, str
 		/* Re-load page tables */
 		cur_pgd = next->pgd;
 		queue_pt_switch(__pa(cur_pgd));
-		XENO_flush_page_update_queue();
+		MULTICALL_flush_page_update_queue();
 	}
 #ifdef CONFIG_SMP
 	else {
@@ -70,6 +72,10 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, str
 }
 
 #define activate_mm(prev, next) \
-	switch_mm((prev),(next),NULL,smp_processor_id())
+do { \
+	switch_mm((prev),(next),NULL,smp_processor_id()); \
+	execute_multicall_list(); \
+	sti(); /* matches 'cli' in switch_mm() */ \
+} while ( 0 )
 
 #endif
diff --git a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/multicall.h b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/multicall.h
new file mode 100644
index 0000000000..27126dcaac
--- /dev/null
+++ b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/multicall.h
@@ -0,0 +1,45 @@
+/******************************************************************************
+ * multicall.h
+ */
+
+#ifndef __MULTICALL_H__
+#define __MULTICALL_H__
+
+#include <asm/hypervisor.h>
+
+extern multicall_entry_t multicall_list[];
+extern int nr_multicall_ents;
+
+static inline void queue_multicall0(unsigned long op)
+{
+    int i = nr_multicall_ents;
+    multicall_list[i].op      = op;
+    nr_multicall_ents = i+1;
+}
+
+static inline void queue_multicall1(unsigned long op, unsigned long arg1)
+{
+    int i = nr_multicall_ents;
+    multicall_list[i].op      = op;
+    multicall_list[i].args[0] = arg1;
+    nr_multicall_ents = i+1;
+}
+
+static inline void queue_multicall2(
+    unsigned long op, unsigned long arg1, unsigned long arg2)
+{
+    int i = nr_multicall_ents;
+    multicall_list[i].op      = op;
+    multicall_list[i].args[0] = arg1;
+    multicall_list[i].args[1] = arg2;
+    nr_multicall_ents = i+1;
+}
+
+static inline void execute_multicall_list(void)
+{
+    if ( unlikely(nr_multicall_ents == 0) ) return;
+    (void)HYPERVISOR_multicall(multicall_list, nr_multicall_ents);
+    nr_multicall_ents = 0;
+}
+
+#endif /* __MULTICALL_H__ */