xen: add debugfs support
Add support for exporting statistics on mmu updates, multicall
batching and pv spinlocks into debugfs. The base path is xen/ and
each subsystem adds its own directory: mmu, multicalls, spinlocks.
In each directory, writing 1 to "zero_stats" will cause the
corresponding stats to be zeroed the next time they're updated.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/xen/multicalls.c b/arch/x86/xen/multicalls.c
index 9efd1c6..8ea8a0d 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 @@
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 @@
something in the middle */
local_irq_save(flags);
+ mc_add_stats(b);
+
if (b->mcidx) {
#if MC_DEBUG
memcpy(b->debug, b->entries,
@@ -115,6 +191,7 @@
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));
}
@@ -158,10 +235,44 @@
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 */