1 files changed, 114 insertions, 2 deletions

diff --git a/arch/x86/xen/multicalls.c b/arch/x86/xen/multicalls.c
index 3c63c4da7ed1..8ea8a0d0b0de 100644
--- a/arch/x86/xen/multicalls.c
+++ b/arch/x86/xen/multicalls.c
@@ -21,16 +21,20 @@
  */
 #include <linux/percpu.h>
 #include <linux/hardirq.h>
+#include <linux/debugfs.h>
 
 #include <asm/xen/hypercall.h>
 
 #include "multicalls.h"
+#include "debugfs.h"
+
+#define MC_BATCH        32
 
 #define MC_DEBUG        1
 
-#define MC_BATCH        32
 #define MC_ARGS         (MC_BATCH * 16)
 
+
 struct mc_buffer {
         struct multicall_entry entries[MC_BATCH];
 #if MC_DEBUG
@@ -47,6 +51,76 @@ struct mc_buffer {
 static DEFINE_PER_CPU(struct mc_buffer, mc_buffer);
 DEFINE_PER_CPU(unsigned long, xen_mc_irq_flags);
 
+/* flush reasons 0- slots, 1- args, 2- callbacks */
+enum flush_reasons
+{
+        FL_SLOTS,
+        FL_ARGS,
+        FL_CALLBACKS,
+
+        FL_N_REASONS
+};
+
+#ifdef CONFIG_XEN_DEBUG_FS
+#define NHYPERCALLS     40              /* not really */
+
+static struct {
+        unsigned histo[MC_BATCH+1];
+
+        unsigned issued;
+        unsigned arg_total;
+        unsigned hypercalls;
+        unsigned histo_hypercalls[NHYPERCALLS];
+
+        unsigned flush[FL_N_REASONS];
+} mc_stats;
+
+static u8 zero_stats;
+
+static inline void check_zero(void)
+{
+        if (unlikely(zero_stats)) {
+                memset(&mc_stats, 0, sizeof(mc_stats));
+                zero_stats = 0;
+        }
+}
+
+static void mc_add_stats(const struct mc_buffer *mc)
+{
+        int i;
+
+        check_zero();
+
+        mc_stats.issued++;
+        mc_stats.hypercalls += mc->mcidx;
+        mc_stats.arg_total += mc->argidx;
+
+        mc_stats.histo[mc->mcidx]++;
+        for(i = 0; i < mc->mcidx; i++) {
+                unsigned op = mc->entries[i].op;
+                if (op < NHYPERCALLS)
+                        mc_stats.histo_hypercalls[op]++;
+        }
+}
+
+static void mc_stats_flush(enum flush_reasons idx)
+{
+        check_zero();
+
+        mc_stats.flush[idx]++;
+}
+
+#else  /* !CONFIG_XEN_DEBUG_FS */
+
+static inline void mc_add_stats(const struct mc_buffer *mc)
+{
+}
+
+static inline void mc_stats_flush(enum flush_reasons idx)
+{
+}
+#endif  /* CONFIG_XEN_DEBUG_FS */
+
 void xen_mc_flush(void)
 {
         struct mc_buffer *b = &__get_cpu_var(mc_buffer);
@@ -60,6 +134,8 @@ void xen_mc_flush(void)
            something in the middle */
         local_irq_save(flags);
 
+        mc_add_stats(b);
+
         if (b->mcidx) {
 #if MC_DEBUG
                 memcpy(b->debug, b->entries,
@@ -76,6 +152,7 @@ void xen_mc_flush(void)
                 if (ret) {
                         printk(KERN_ERR "%d multicall(s) failed: cpu %d\n",
                                ret, smp_processor_id());
+                        dump_stack();
                         for (i = 0; i < b->mcidx; i++) {
                                 printk("  call %2d/%d: op=%lu arg=[%lx] result=%ld\n",
                                        i+1, b->mcidx,
@@ -114,6 +191,7 @@ struct multicall_space __xen_mc_entry(size_t args)
 
         if (b->mcidx == MC_BATCH ||
             (argidx + args) > MC_ARGS) {
+                mc_stats_flush(b->mcidx == MC_BATCH ? FL_SLOTS : FL_ARGS);
                 xen_mc_flush();
                 argidx = roundup(b->argidx, sizeof(u64));
         }
@@ -157,10 +235,44 @@ void xen_mc_callback(void (*fn)(void *), void *data)
         struct mc_buffer *b = &__get_cpu_var(mc_buffer);
         struct callback *cb;
 
-        if (b->cbidx == MC_BATCH)
+        if (b->cbidx == MC_BATCH) {
+                mc_stats_flush(FL_CALLBACKS);
                 xen_mc_flush();
+        }
 
         cb = &b->callbacks[b->cbidx++];
         cb->fn = fn;
         cb->data = data;
 }
+
+#ifdef CONFIG_XEN_DEBUG_FS
+
+static struct dentry *d_mc_debug;
+
+static int __init xen_mc_debugfs(void)
+{
+        struct dentry *d_xen = xen_init_debugfs();
+
+        if (d_xen == NULL)
+                return -ENOMEM;
+
+        d_mc_debug = debugfs_create_dir("multicalls", d_xen);
+
+        debugfs_create_u8("zero_stats", 0644, d_mc_debug, &zero_stats);
+
+        debugfs_create_u32("batches", 0444, d_mc_debug, &mc_stats.issued);
+        debugfs_create_u32("hypercalls", 0444, d_mc_debug, &mc_stats.hypercalls);
+        debugfs_create_u32("arg_total", 0444, d_mc_debug, &mc_stats.arg_total);
+
+        xen_debugfs_create_u32_array("batch_histo", 0444, d_mc_debug,
+                                     mc_stats.histo, MC_BATCH);
+        xen_debugfs_create_u32_array("hypercall_histo", 0444, d_mc_debug,
+                                     mc_stats.histo_hypercalls, NHYPERCALLS);
+        xen_debugfs_create_u32_array("flush_reasons", 0444, d_mc_debug,
+                                     mc_stats.flush, FL_N_REASONS);
+
+        return 0;
+}
+fs_initcall(xen_mc_debugfs);
+
+#endif  /* CONFIG_XEN_DEBUG_FS */