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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 2 of 4] 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@xxxxxxxxxx>
---
arch/x86/xen/Kconfig | 10 ++
arch/x86/xen/Makefile | 3
arch/x86/xen/debugfs.c | 123 +++++++++++++++++++++++++++++++++
arch/x86/xen/debugfs.h | 10 ++
arch/x86/xen/mmu.c | 163 +++++++++++++++++++++++++++++++++++++++++++-
arch/x86/xen/multicalls.c | 115 ++++++++++++++++++++++++++++++-
arch/x86/xen/spinlock.c | 165 ++++++++++++++++++++++++++++++++++++++++++++-
7 files changed, 580 insertions(+), 9 deletions(-)
diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -27,4 +27,12 @@
config XEN_SAVE_RESTORE
bool
depends on PM
- default y
\ No newline at end of file
+ default y
+
+config XEN_DEBUG_FS
+ bool "Enable Xen debug and tuning parameters in debugfs"
+ depends on XEN && DEBUG_FS
+ default n
+ help
+ Enable statistics output and various tuning options in debugfs.
+ Enabling this option may incur a significant performance overhead.
\ No newline at end of file
diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile
--- a/arch/x86/xen/Makefile
+++ b/arch/x86/xen/Makefile
@@ -8,4 +8,5 @@
obj-y := enlighten.o setup.o multicalls.o mmu.o irq.o \
time.o xen-asm_$(BITS).o grant-table.o suspend.o
-obj-$(CONFIG_SMP) += smp.o spinlock.o
+obj-$(CONFIG_SMP) += smp.o spinlock.o
+obj-$(CONFIG_XEN_DEBUG_FS) += debugfs.o
\ No newline at end of file
diff --git a/arch/x86/xen/debugfs.c b/arch/x86/xen/debugfs.c
new file mode 100644
--- /dev/null
+++ b/arch/x86/xen/debugfs.c
@@ -0,0 +1,123 @@
+#include <linux/init.h>
+#include <linux/debugfs.h>
+#include <linux/module.h>
+
+#include "debugfs.h"
+
+static struct dentry *d_xen_debug;
+
+struct dentry * __init xen_init_debugfs(void)
+{
+ if (!d_xen_debug) {
+ d_xen_debug = debugfs_create_dir("xen", NULL);
+
+ if (!d_xen_debug)
+ pr_warning("Could not create 'xen' debugfs
directory\n");
+ }
+
+ return d_xen_debug;
+}
+
+struct array_data
+{
+ void *array;
+ unsigned elements;
+};
+
+static int u32_array_open(struct inode *inode, struct file *file)
+{
+ file->private_data = NULL;
+ return nonseekable_open(inode, file);
+}
+
+static size_t format_array(char *buf, size_t bufsize, const char *fmt,
+ u32 *array, unsigned array_size)
+{
+ size_t ret = 0;
+ unsigned i;
+
+ for(i = 0; i < array_size; i++) {
+ size_t len;
+
+ len = snprintf(buf, bufsize, fmt, array[i]);
+ len++; /* ' ' or '\n' */
+ ret += len;
+
+ if (buf) {
+ buf += len;
+ bufsize -= len;
+ buf[-1] = (i == array_size-1) ? '\n' : ' ';
+ }
+ }
+
+ ret++; /* \0 */
+ if (buf)
+ *buf = '\0';
+
+ return ret;
+}
+
+static char *format_array_alloc(const char *fmt, u32 *array, unsigned
array_size)
+{
+ size_t len = format_array(NULL, 0, fmt, array, array_size);
+ char *ret;
+
+ ret = kmalloc(len, GFP_KERNEL);
+ if (ret == NULL)
+ return NULL;
+
+ format_array(ret, len, fmt, array, array_size);
+ return ret;
+}
+
+static ssize_t u32_array_read(struct file *file, char __user *buf, size_t len,
+ loff_t *ppos)
+{
+ struct inode *inode = file->f_path.dentry->d_inode;
+ struct array_data *data = inode->i_private;
+ size_t size;
+
+ if (*ppos == 0) {
+ if (file->private_data) {
+ kfree(file->private_data);
+ file->private_data = NULL;
+ }
+
+ file->private_data = format_array_alloc("%u", data->array,
data->elements);
+ }
+
+ size = 0;
+ if (file->private_data)
+ size = strlen(file->private_data);
+
+ return simple_read_from_buffer(buf, len, ppos, file->private_data,
size);
+}
+
+static int xen_array_release(struct inode *inode, struct file *file)
+{
+ kfree(file->private_data);
+
+ return 0;
+}
+
+static struct file_operations u32_array_fops = {
+ .owner = THIS_MODULE,
+ .open = u32_array_open,
+ .release= xen_array_release,
+ .read = u32_array_read,
+};
+
+struct dentry *xen_debugfs_create_u32_array(const char *name, mode_t mode,
+ struct dentry *parent,
+ u32 *array, unsigned elements)
+{
+ struct array_data *data = kmalloc(sizeof(*data), GFP_KERNEL);
+
+ if (data == NULL)
+ return NULL;
+
+ data->array = array;
+ data->elements = elements;
+
+ return debugfs_create_file(name, mode, parent, data, &u32_array_fops);
+}
diff --git a/arch/x86/xen/debugfs.h b/arch/x86/xen/debugfs.h
new file mode 100644
--- /dev/null
+++ b/arch/x86/xen/debugfs.h
@@ -0,0 +1,10 @@
+#ifndef _XEN_DEBUGFS_H
+#define _XEN_DEBUGFS_H
+
+struct dentry * __init xen_init_debugfs(void);
+
+struct dentry *xen_debugfs_create_u32_array(const char *name, mode_t mode,
+ struct dentry *parent,
+ u32 *array, unsigned elements);
+
+#endif /* _XEN_DEBUGFS_H */
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -40,6 +40,7 @@
*/
#include <linux/sched.h>
#include <linux/highmem.h>
+#include <linux/debugfs.h>
#include <linux/bug.h>
#include <asm/pgtable.h>
@@ -57,6 +58,61 @@
#include "multicalls.h"
#include "mmu.h"
+#include "debugfs.h"
+
+#define MMU_UPDATE_HISTO 30
+
+#ifdef CONFIG_XEN_DEBUG_FS
+
+static struct {
+ u32 pgd_update;
+ u32 pgd_update_pinned;
+ u32 pgd_update_batched;
+
+ u32 pud_update;
+ u32 pud_update_pinned;
+ u32 pud_update_batched;
+
+ u32 pmd_update;
+ u32 pmd_update_pinned;
+ u32 pmd_update_batched;
+
+ u32 pte_update;
+ u32 pte_update_pinned;
+ u32 pte_update_batched;
+
+ u32 mmu_update;
+ u32 mmu_update_extended;
+ u32 mmu_update_histo[MMU_UPDATE_HISTO];
+
+ u32 prot_commit;
+ u32 prot_commit_batched;
+
+ u32 set_pte_at;
+ u32 set_pte_at_batched;
+ u32 set_pte_at_pinned;
+ u32 set_pte_at_current;
+ u32 set_pte_at_kernel;
+} mmu_stats;
+
+static u8 zero_stats;
+
+static inline void check_zero(void)
+{
+ if (unlikely(zero_stats)) {
+ memset(&mmu_stats, 0, sizeof(mmu_stats));
+ zero_stats = 0;
+ }
+}
+
+#define ADD_STATS(elem, val) \
+ do { check_zero(); mmu_stats.elem += (val); } while(0)
+
+#else /* !CONFIG_XEN_DEBUG_FS */
+
+#define ADD_STATS(elem, val) do { (void)(val); } while(0)
+
+#endif /* CONFIG_XEN_DEBUG_FS */
/*
* Just beyond the highest usermode address. STACK_TOP_MAX has a
@@ -243,11 +299,21 @@
mcs = xen_mc_extend_args(__HYPERVISOR_mmu_update, sizeof(*u));
- if (mcs.mc != NULL)
+ if (mcs.mc != NULL) {
+ ADD_STATS(mmu_update_extended, 1);
+ ADD_STATS(mmu_update_histo[mcs.mc->args[1]], -1);
+
mcs.mc->args[1]++;
- else {
+
+ if (mcs.mc->args[1] < MMU_UPDATE_HISTO)
+ ADD_STATS(mmu_update_histo[mcs.mc->args[1]], 1);
+ else
+ ADD_STATS(mmu_update_histo[0], 1);
+ } else {
+ ADD_STATS(mmu_update, 1);
mcs = __xen_mc_entry(sizeof(*u));
MULTI_mmu_update(mcs.mc, mcs.args, 1, NULL, DOMID_SELF);
+ ADD_STATS(mmu_update_histo[1], 1);
}
u = mcs.args;
@@ -267,6 +333,8 @@
u.val = pmd_val_ma(val);
xen_extend_mmu_update(&u);
+ ADD_STATS(pmd_update_batched, paravirt_get_lazy_mode() ==
PARAVIRT_LAZY_MMU);
+
xen_mc_issue(PARAVIRT_LAZY_MMU);
preempt_enable();
@@ -274,12 +342,16 @@
void xen_set_pmd(pmd_t *ptr, pmd_t val)
{
+ ADD_STATS(pmd_update, 1);
+
/* If page is not pinned, we can just update the entry
directly */
if (!xen_page_pinned(ptr)) {
*ptr = val;
return;
}
+
+ ADD_STATS(pmd_update_pinned, 1);
xen_set_pmd_hyper(ptr, val);
}
@@ -300,12 +372,18 @@
if (mm == &init_mm)
preempt_disable();
+ ADD_STATS(set_pte_at, 1);
+// ADD_STATS(set_pte_at_pinned, xen_page_pinned(ptep));
+ ADD_STATS(set_pte_at_current, mm == current->mm);
+ ADD_STATS(set_pte_at_kernel, mm == &init_mm);
+
if (mm == current->mm || mm == &init_mm) {
if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
struct multicall_space mcs;
mcs = xen_mc_entry(0);
MULTI_update_va_mapping(mcs.mc, addr, pteval, 0);
+ ADD_STATS(set_pte_at_batched, 1);
xen_mc_issue(PARAVIRT_LAZY_MMU);
goto out;
} else
@@ -335,6 +413,9 @@
u.ptr = virt_to_machine(ptep).maddr | MMU_PT_UPDATE_PRESERVE_AD;
u.val = pte_val_ma(pte);
xen_extend_mmu_update(&u);
+
+ ADD_STATS(prot_commit, 1);
+ ADD_STATS(prot_commit_batched, paravirt_get_lazy_mode() ==
PARAVIRT_LAZY_MMU);
xen_mc_issue(PARAVIRT_LAZY_MMU);
}
@@ -402,6 +483,8 @@
u.val = pud_val_ma(val);
xen_extend_mmu_update(&u);
+ ADD_STATS(pud_update_batched, paravirt_get_lazy_mode() ==
PARAVIRT_LAZY_MMU);
+
xen_mc_issue(PARAVIRT_LAZY_MMU);
preempt_enable();
@@ -409,6 +492,8 @@
void xen_set_pud(pud_t *ptr, pud_t val)
{
+ ADD_STATS(pud_update, 1);
+
/* If page is not pinned, we can just update the entry
directly */
if (!xen_page_pinned(ptr)) {
@@ -416,11 +501,17 @@
return;
}
+ ADD_STATS(pud_update_pinned, 1);
+
xen_set_pud_hyper(ptr, val);
}
void xen_set_pte(pte_t *ptep, pte_t pte)
{
+ ADD_STATS(pte_update, 1);
+// ADD_STATS(pte_update_pinned, xen_page_pinned(ptep));
+ ADD_STATS(pte_update_batched, paravirt_get_lazy_mode() ==
PARAVIRT_LAZY_MMU);
+
#ifdef CONFIG_X86_PAE
ptep->pte_high = pte.pte_high;
smp_wmb();
@@ -517,6 +608,8 @@
{
pgd_t *user_ptr = xen_get_user_pgd(ptr);
+ ADD_STATS(pgd_update, 1);
+
/* If page is not pinned, we can just update the entry
directly */
if (!xen_page_pinned(ptr)) {
@@ -527,6 +620,9 @@
}
return;
}
+
+ ADD_STATS(pgd_update_pinned, 1);
+ ADD_STATS(pgd_update_batched, paravirt_get_lazy_mode() ==
PARAVIRT_LAZY_MMU);
/* If it's pinned, then we can at least batch the kernel and
user updates together. */
@@ -1003,3 +1099,66 @@
spin_unlock(&mm->page_table_lock);
}
+
+#ifdef CONFIG_XEN_DEBUG_FS
+
+static struct dentry *d_mmu_debug;
+
+static int __init xen_mmu_debugfs(void)
+{
+ struct dentry *d_xen = xen_init_debugfs();
+
+ if (d_xen == NULL)
+ return -ENOMEM;
+
+ d_mmu_debug = debugfs_create_dir("mmu", d_xen);
+
+ debugfs_create_u8("zero_stats", 0644, d_mmu_debug, &zero_stats);
+
+ debugfs_create_u32("pgd_update", 0444, d_mmu_debug,
&mmu_stats.pgd_update);
+ debugfs_create_u32("pgd_update_pinned", 0444, d_mmu_debug,
+ &mmu_stats.pgd_update_pinned);
+ debugfs_create_u32("pgd_update_batched", 0444, d_mmu_debug,
+ &mmu_stats.pgd_update_pinned);
+
+ debugfs_create_u32("pud_update", 0444, d_mmu_debug,
&mmu_stats.pud_update);
+ debugfs_create_u32("pud_update_pinned", 0444, d_mmu_debug,
+ &mmu_stats.pud_update_pinned);
+ debugfs_create_u32("pud_update_batched", 0444, d_mmu_debug,
+ &mmu_stats.pud_update_pinned);
+
+ debugfs_create_u32("pmd_update", 0444, d_mmu_debug,
&mmu_stats.pmd_update);
+ debugfs_create_u32("pmd_update_pinned", 0444, d_mmu_debug,
+ &mmu_stats.pmd_update_pinned);
+ debugfs_create_u32("pmd_update_batched", 0444, d_mmu_debug,
+ &mmu_stats.pmd_update_pinned);
+
+ debugfs_create_u32("pte_update", 0444, d_mmu_debug,
&mmu_stats.pte_update);
+// debugfs_create_u32("pte_update_pinned", 0444, d_mmu_debug,
+// &mmu_stats.pte_update_pinned);
+ debugfs_create_u32("pte_update_batched", 0444, d_mmu_debug,
+ &mmu_stats.pte_update_pinned);
+
+ debugfs_create_u32("mmu_update", 0444, d_mmu_debug,
&mmu_stats.mmu_update);
+ debugfs_create_u32("mmu_update_extended", 0444, d_mmu_debug,
+ &mmu_stats.mmu_update_extended);
+ xen_debugfs_create_u32_array("mmu_update_histo", 0444, d_mmu_debug,
+ mmu_stats.mmu_update_histo, 20);
+
+ debugfs_create_u32("set_pte_at", 0444, d_mmu_debug,
&mmu_stats.set_pte_at);
+ debugfs_create_u32("set_pte_at_batched", 0444, d_mmu_debug,
+ &mmu_stats.set_pte_at_batched);
+ debugfs_create_u32("set_pte_at_current", 0444, d_mmu_debug,
+ &mmu_stats.set_pte_at_current);
+ debugfs_create_u32("set_pte_at_kernel", 0444, d_mmu_debug,
+ &mmu_stats.set_pte_at_kernel);
+
+ debugfs_create_u32("prot_commit", 0444, d_mmu_debug,
&mmu_stats.prot_commit);
+ debugfs_create_u32("prot_commit_batched", 0444, d_mmu_debug,
+ &mmu_stats.prot_commit_batched);
+
+ return 0;
+}
+fs_initcall(xen_mmu_debugfs);
+
+#endif /* CONFIG_XEN_DEBUG_FS */
diff --git a/arch/x86/xen/multicalls.c b/arch/x86/xen/multicalls.c
--- a/arch/x86/xen/multicalls.c
+++ b/arch/x86/xen/multicalls.c
@@ -21,15 +21,19 @@
*/
#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];
@@ -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);
@@ -59,6 +133,8 @@
/* Disable interrupts in case someone comes in and queues
something in the middle */
local_irq_save(flags);
+
+ mc_add_stats(b);
if (b->mcidx) {
#if MC_DEBUG
@@ -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 */
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -4,6 +4,8 @@
*/
#include <linux/kernel_stat.h>
#include <linux/spinlock.h>
+#include <linux/debugfs.h>
+#include <linux/log2.h>
#include <asm/paravirt.h>
@@ -11,6 +13,93 @@
#include <xen/events.h>
#include "xen-ops.h"
+#include "debugfs.h"
+
+#ifdef CONFIG_XEN_DEBUG_FS
+static struct xen_spinlock_stats
+{
+ u64 taken;
+ u32 taken_slow;
+ u32 taken_slow_nested;
+ u32 taken_slow_pickup;
+ u32 taken_slow_spurious;
+
+ u64 released;
+ u32 released_slow;
+ u32 released_slow_kicked;
+
+#define HISTO_BUCKETS 20
+ u32 histo_spin_fast[HISTO_BUCKETS+1];
+ u32 histo_spin[HISTO_BUCKETS+1];
+
+ u64 spinning_time;
+ u64 total_time;
+} spinlock_stats;
+
+static u8 zero_stats;
+
+static unsigned lock_timeout = 1 << 10;
+#define TIMEOUT lock_timeout
+
+static inline void check_zero(void)
+{
+ if (unlikely(zero_stats)) {
+ memset(&spinlock_stats, 0, sizeof(spinlock_stats));
+ zero_stats = 0;
+ }
+}
+
+#define ADD_STATS(elem, val) \
+ do { check_zero(); spinlock_stats.elem += (val); } while(0)
+
+static inline u64 spin_time_start(void)
+{
+ return xen_clocksource_read();
+}
+
+static void __spin_time_accum(u64 delta, u32 *array)
+{
+ unsigned index = ilog2(delta);
+
+ check_zero();
+
+ if (index < HISTO_BUCKETS)
+ array[index]++;
+ else
+ array[HISTO_BUCKETS]++;
+}
+
+static inline void spin_time_accum_fast(u64 start)
+{
+ u32 delta = xen_clocksource_read() - start;
+
+ __spin_time_accum(delta, spinlock_stats.histo_spin_fast);
+ spinlock_stats.spinning_time += delta;
+}
+
+static inline void spin_time_accum(u64 start)
+{
+ u32 delta = xen_clocksource_read() - start;
+
+ __spin_time_accum(delta, spinlock_stats.histo_spin);
+ spinlock_stats.total_time += delta;
+}
+#else /* !CONFIG_XEN_DEBUG_FS */
+#define TIMEOUT (1 << 10)
+#define ADD_STATS(elem, val) do { (void)(val); } while(0)
+
+static inline u64 spin_time_start(void)
+{
+ return 0;
+}
+
+static inline void spin_time_accum_fast(u64 start)
+{
+}
+static inline void spin_time_accum(u64 start)
+{
+}
+#endif /* CONFIG_XEN_DEBUG_FS */
struct xen_spinlock {
unsigned char lock; /* 0 -> free; 1 -> locked */
@@ -92,6 +181,9 @@
/* announce we're spinning */
prev = spinning_lock(xl);
+ ADD_STATS(taken_slow, 1);
+ ADD_STATS(taken_slow_nested, prev != NULL);
+
do {
/* clear pending */
xen_clear_irq_pending(irq);
@@ -100,6 +192,8 @@
we weren't looking */
ret = xen_spin_trylock(lock);
if (ret) {
+ ADD_STATS(taken_slow_pickup, 1);
+
/*
* If we interrupted another spinlock while it
* was blocking, make sure it doesn't block
@@ -120,6 +214,7 @@
* pending.
*/
xen_poll_irq(irq);
+ ADD_STATS(taken_slow_spurious, !xen_test_irq_pending(irq));
} while (!xen_test_irq_pending(irq)); /* check for spurious wakeups */
kstat_irqs_this_cpu(irq_to_desc(irq))++;
@@ -132,11 +227,18 @@
static void xen_spin_lock(struct raw_spinlock *lock)
{
struct xen_spinlock *xl = (struct xen_spinlock *)lock;
- int timeout;
+ unsigned timeout;
u8 oldval;
+ u64 start_spin;
+
+ ADD_STATS(taken, 1);
+
+ start_spin = spin_time_start();
do {
- timeout = 1 << 10;
+ u64 start_spin_fast = spin_time_start();
+
+ timeout = TIMEOUT;
asm("1: xchgb %1,%0\n"
" testb %1,%1\n"
@@ -151,16 +253,22 @@
: "1" (1)
: "memory");
- } while (unlikely(oldval != 0 && !xen_spin_lock_slow(lock)));
+ spin_time_accum_fast(start_spin_fast);
+ } while (unlikely(oldval != 0 && (TIMEOUT == ~0 ||
!xen_spin_lock_slow(lock))));
+
+ spin_time_accum(start_spin);
}
static noinline void xen_spin_unlock_slow(struct xen_spinlock *xl)
{
int cpu;
+ ADD_STATS(released_slow, 1);
+
for_each_online_cpu(cpu) {
/* XXX should mix up next cpu selection */
if (per_cpu(lock_spinners, cpu) == xl) {
+ ADD_STATS(released_slow_kicked, 1);
xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
break;
}
@@ -170,6 +278,8 @@
static void xen_spin_unlock(struct raw_spinlock *lock)
{
struct xen_spinlock *xl = (struct xen_spinlock *)lock;
+
+ ADD_STATS(released, 1);
smp_wmb(); /* make sure no writes get moved after unlock */
xl->lock = 0; /* release lock */
@@ -216,3 +326,52 @@
pv_lock_ops.spin_trylock = xen_spin_trylock;
pv_lock_ops.spin_unlock = xen_spin_unlock;
}
+
+#ifdef CONFIG_XEN_DEBUG_FS
+
+static struct dentry *d_spin_debug;
+
+static int __init xen_spinlock_debugfs(void)
+{
+ struct dentry *d_xen = xen_init_debugfs();
+
+ if (d_xen == NULL)
+ return -ENOMEM;
+
+ d_spin_debug = debugfs_create_dir("spinlocks", d_xen);
+
+ debugfs_create_u8("zero_stats", 0644, d_spin_debug, &zero_stats);
+
+ debugfs_create_u32("timeout", 0644, d_spin_debug, &lock_timeout);
+
+ debugfs_create_u64("taken", 0444, d_spin_debug, &spinlock_stats.taken);
+ debugfs_create_u32("taken_slow", 0444, d_spin_debug,
+ &spinlock_stats.taken_slow);
+ debugfs_create_u32("taken_slow_nested", 0444, d_spin_debug,
+ &spinlock_stats.taken_slow_nested);
+ debugfs_create_u32("taken_slow_pickup", 0444, d_spin_debug,
+ &spinlock_stats.taken_slow_pickup);
+ debugfs_create_u32("taken_slow_spurious", 0444, d_spin_debug,
+ &spinlock_stats.taken_slow_spurious);
+
+ debugfs_create_u64("released", 0444, d_spin_debug,
&spinlock_stats.released);
+ debugfs_create_u32("released_slow", 0444, d_spin_debug,
+ &spinlock_stats.released_slow);
+ debugfs_create_u32("released_slow_kicked", 0444, d_spin_debug,
+ &spinlock_stats.released_slow_kicked);
+
+ debugfs_create_u64("time_spinning", 0444, d_spin_debug,
+ &spinlock_stats.spinning_time);
+ debugfs_create_u64("time_total", 0444, d_spin_debug,
+ &spinlock_stats.total_time);
+
+ xen_debugfs_create_u32_array("histo_total", 0444, d_spin_debug,
+ spinlock_stats.histo_spin, HISTO_BUCKETS +
1);
+ xen_debugfs_create_u32_array("histo_spinning", 0444, d_spin_debug,
+ spinlock_stats.histo_spin_fast,
HISTO_BUCKETS + 1);
+
+ return 0;
+}
+fs_initcall(xen_spinlock_debugfs);
+
+#endif /* CONFIG_XEN_DEBUG_FS */
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