Oprofile Multiplexing Patch
Jason Yeh [Wed, 23 Jul 2008 21:05:53 +0000 (23:05 +0200)]
This patch introduces multiplexing support for the Oprofile kernel
module. It basically adds a new function pointer in oprofile_operator
allowing each architecture to supply its callback to switch between
different sets of event when the timer expires. Userspace tools can
modify the time slice through /dev/oprofile/time_slice.

It also modifies the number of counters exposed to the userspace through
/dev/oprofile. For example, the number of counters for AMD CPUs are
changed to 32 and multiplexed in the sets of 4.

Signed-off-by: Jason Yeh <jason.yeh@amd.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>
Cc: oprofile-list <oprofile-list@lists.sourceforge.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/oprofile/nmi_int.c
arch/x86/oprofile/op_counter.h
arch/x86/oprofile/op_model_amd.c
arch/x86/oprofile/op_model_p4.c
arch/x86/oprofile/op_model_ppro.c
arch/x86/oprofile/op_x86_model.h
drivers/oprofile/oprof.c
drivers/oprofile/oprof.h
drivers/oprofile/oprofile_files.c
include/linux/oprofile.h

index 287513a..2a65fe7 100644 (file)
 #include "op_counter.h"
 #include "op_x86_model.h"
 
+DEFINE_PER_CPU(int, switch_index);
+
 static struct op_x86_model_spec const *model;
 static DEFINE_PER_CPU(struct op_msrs, cpu_msrs);
 static DEFINE_PER_CPU(unsigned long, saved_lvtpc);
 
 static int nmi_start(void);
 static void nmi_stop(void);
+static void nmi_cpu_save_mpx_registers(struct op_msrs *msrs);
+static void nmi_cpu_restore_mpx_registers(struct op_msrs *msrs);
+static void nmi_cpu_stop(void *dummy);
+static void nmi_cpu_start(void *dummy);
 
 /* 0 == registered but off, 1 == registered and on */
 static int nmi_enabled = 0;
@@ -81,6 +87,47 @@ static void exit_sysfs(void)
 #define exit_sysfs() do { } while (0)
 #endif /* CONFIG_PM */
 
+static void nmi_cpu_switch(void *dummy)
+{
+       int cpu = smp_processor_id();
+       int si = per_cpu(switch_index, cpu);
+       struct op_msrs *msrs = &per_cpu(cpu_msrs, cpu);
+
+       nmi_cpu_stop(NULL);
+       nmi_cpu_save_mpx_registers(msrs);
+
+       /* move to next set */
+       si += model->num_hardware_counters;
+       if ((si > model->num_counters) || (counter_config[si].count == 0))
+               per_cpu(switch_index, smp_processor_id()) = 0;
+       else
+               per_cpu(switch_index, smp_processor_id()) = si;
+
+       nmi_cpu_restore_mpx_registers(msrs);
+       model->setup_ctrs(msrs);
+       nmi_cpu_start(NULL);
+}
+
+/*
+ * Quick check to see if multiplexing is necessary.
+ * The check should be sufficient since counters are used
+ * in ordre.
+ */
+static int nmi_multiplex_on(void)
+{
+       return counter_config[model->num_hardware_counters].count ? 0 : -EINVAL;
+}
+
+static int nmi_switch_event(void)
+{
+       if (nmi_multiplex_on() < 0)
+               return -EINVAL;
+
+       on_each_cpu(nmi_cpu_switch, NULL, 0, 1);
+
+       return 0;
+}
+
 static int profile_exceptions_notify(struct notifier_block *self,
                                     unsigned long val, void *data)
 {
@@ -144,11 +191,10 @@ static void free_msrs(void)
 
 static int allocate_msrs(void)
 {
-       int success = 1;
+       int i, success = 1;
        size_t controls_size = sizeof(struct op_msr) * model->num_controls;
        size_t counters_size = sizeof(struct op_msr) * model->num_counters;
 
-       int i;
        for_each_possible_cpu(i) {
                per_cpu(cpu_msrs, i).counters = kmalloc(counters_size,
                                                                GFP_KERNEL);
@@ -156,8 +202,8 @@ static int allocate_msrs(void)
                        success = 0;
                        break;
                }
-               per_cpu(cpu_msrs, i).controls = kmalloc(controls_size,
-                                                               GFP_KERNEL);
+               per_cpu(cpu_msrs, i).controls =
+                               kmalloc(controls_size, GFP_KERNEL);
                if (!per_cpu(cpu_msrs, i).controls) {
                        success = 0;
                        break;
@@ -201,7 +247,8 @@ static int nmi_setup(void)
                return err;
        }
 
-       /* We need to serialize save and setup for HT because the subset
+       /*
+        * We need to serialize save and setup for HT because the subset
         * of msrs are distinct for save and setup operations
         */
 
@@ -217,7 +264,6 @@ static int nmi_setup(void)
                                per_cpu(cpu_msrs, 0).controls,
                                sizeof(struct op_msr) * model->num_controls);
                }
-
        }
        on_each_cpu(nmi_save_registers, NULL, 1);
        on_each_cpu(nmi_cpu_setup, NULL, 1);
@@ -225,7 +271,41 @@ static int nmi_setup(void)
        return 0;
 }
 
-static void nmi_restore_registers(struct op_msrs *msrs)
+static void nmi_cpu_save_mpx_registers(struct op_msrs *msrs)
+{
+       unsigned int si = __get_cpu_var(switch_index);
+       unsigned int const nr_ctrs = model->num_hardware_counters;
+       struct op_msr *counters = &msrs->counters[si];
+       unsigned int i;
+
+       for (i = 0; i < nr_ctrs; ++i) {
+               int offset = i + si;
+               if (counters[offset].addr) {
+                       rdmsr(counters[offset].addr,
+                               counters[offset].multiplex.low,
+                               counters[offset].multiplex.high);
+               }
+       }
+}
+
+static void nmi_cpu_restore_mpx_registers(struct op_msrs *msrs)
+{
+       unsigned int si = __get_cpu_var(switch_index);
+       unsigned int const nr_ctrs = model->num_hardware_counters;
+       struct op_msr *counters = &msrs->counters[si];
+       unsigned int i;
+
+       for (i = 0; i < nr_ctrs; ++i) {
+               int offset = i + si;
+               if (counters[offset].addr) {
+                       wrmsr(counters[offset].addr,
+                               counters[offset].multiplex.low,
+                               counters[offset].multiplex.high);
+               }
+       }
+}
+
+static void nmi_cpu_restore_registers(struct op_msrs *msrs)
 {
        unsigned int const nr_ctrs = model->num_counters;
        unsigned int const nr_ctrls = model->num_controls;
@@ -265,7 +345,8 @@ static void nmi_cpu_shutdown(void *dummy)
        apic_write(APIC_LVTERR, v | APIC_LVT_MASKED);
        apic_write(APIC_LVTPC, per_cpu(saved_lvtpc, cpu));
        apic_write(APIC_LVTERR, v);
-       nmi_restore_registers(msrs);
+       nmi_cpu_restore_registers(msrs);
+       __get_cpu_var(switch_index) = 0;
 }
 
 static void nmi_shutdown(void)
@@ -328,6 +409,7 @@ static int nmi_create_files(struct super_block *sb, struct dentry *root)
                oprofilefs_create_ulong(sb, dir, "unit_mask", &counter_config[i].unit_mask);
                oprofilefs_create_ulong(sb, dir, "kernel", &counter_config[i].kernel);
                oprofilefs_create_ulong(sb, dir, "user", &counter_config[i].user);
+               counter_config[i].save_count_low = 0;
        }
 
        return 0;
@@ -469,12 +551,14 @@ int __init op_nmi_init(struct oprofile_operations *ops)
        }
 
        /* default values, can be overwritten by model */
+       __get_cpu_var(switch_index) = 0;
        ops->create_files = nmi_create_files;
        ops->setup = nmi_setup;
        ops->shutdown = nmi_shutdown;
        ops->start = nmi_start;
        ops->stop = nmi_stop;
        ops->cpu_type = cpu_type;
+       ops->switch_events = nmi_switch_event;
 
        if (model->init)
                ret = model->init(ops);
index 2880b15..786d6e0 100644 (file)
 #ifndef OP_COUNTER_H
 #define OP_COUNTER_H
  
-#define OP_MAX_COUNTER 8
+#define OP_MAX_COUNTER 32
  
 /* Per-perfctr configuration as set via
  * oprofilefs.
  */
 struct op_counter_config {
         unsigned long count;
+               unsigned long save_count_low;
         unsigned long enabled;
         unsigned long event;
         unsigned long kernel;
index d9faf60..bbf2b68 100644 (file)
@@ -15,6 +15,7 @@
 #include <linux/oprofile.h>
 #include <linux/device.h>
 #include <linux/pci.h>
+#include <linux/percpu.h>
 
 #include <asm/ptrace.h>
 #include <asm/msr.h>
 #include "op_x86_model.h"
 #include "op_counter.h"
 
-#define NUM_COUNTERS 4
-#define NUM_CONTROLS 4
+#define NUM_COUNTERS 32
+#define NUM_HARDWARE_COUNTERS 4
+#define NUM_CONTROLS 32
+#define NUM_HARDWARE_CONTROLS 4
 
 #define CTR_IS_RESERVED(msrs, c) (msrs->counters[(c)].addr ? 1 : 0)
 #define CTR_READ(l, h, msrs, c) do {rdmsr(msrs->counters[(c)].addr, (l), (h)); } while (0)
@@ -48,6 +51,7 @@
 #define CTRL_SET_GUEST_ONLY(val, h) (val |= ((h & 1) << 8))
 
 static unsigned long reset_value[NUM_COUNTERS];
+DECLARE_PER_CPU(int, switch_index);
 
 #ifdef CONFIG_OPROFILE_IBS
 
@@ -130,15 +134,17 @@ static void op_amd_fill_in_addresses(struct op_msrs * const msrs)
        int i;
 
        for (i = 0; i < NUM_COUNTERS; i++) {
-               if (reserve_perfctr_nmi(MSR_K7_PERFCTR0 + i))
-                       msrs->counters[i].addr = MSR_K7_PERFCTR0 + i;
+               int hw_counter = i % NUM_HARDWARE_COUNTERS;
+               if (reserve_perfctr_nmi(MSR_K7_PERFCTR0 + hw_counter))
+                       msrs->counters[i].addr = MSR_K7_PERFCTR0 + hw_counter;
                else
                        msrs->counters[i].addr = 0;
        }
 
        for (i = 0; i < NUM_CONTROLS; i++) {
-               if (reserve_evntsel_nmi(MSR_K7_EVNTSEL0 + i))
-                       msrs->controls[i].addr = MSR_K7_EVNTSEL0 + i;
+               int hw_control = i % NUM_HARDWARE_CONTROLS;
+               if (reserve_evntsel_nmi(MSR_K7_EVNTSEL0 + hw_control))
+                       msrs->controls[i].addr = MSR_K7_EVNTSEL0 + hw_control;
                else
                        msrs->controls[i].addr = 0;
        }
@@ -150,8 +156,16 @@ static void op_amd_setup_ctrs(struct op_msrs const * const msrs)
        unsigned int low, high;
        int i;
 
+       for (i = 0; i < NUM_HARDWARE_CONTROLS; ++i) {
+               int offset = i + __get_cpu_var(switch_index);
+               if (counter_config[offset].enabled)
+                       reset_value[offset] = counter_config[offset].count;
+               else
+                       reset_value[offset] = 0;
+       }
+
        /* clear all counters */
-       for (i = 0 ; i < NUM_CONTROLS; ++i) {
+       for (i = 0 ; i < NUM_HARDWARE_CONTROLS; ++i) {
                if (unlikely(!CTRL_IS_RESERVED(msrs, i)))
                        continue;
                CTRL_READ(low, high, msrs, i);
@@ -161,34 +175,31 @@ static void op_amd_setup_ctrs(struct op_msrs const * const msrs)
        }
 
        /* avoid a false detection of ctr overflows in NMI handler */
-       for (i = 0; i < NUM_COUNTERS; ++i) {
+       for (i = 0; i < NUM_HARDWARE_COUNTERS; ++i) {
                if (unlikely(!CTR_IS_RESERVED(msrs, i)))
                        continue;
                CTR_WRITE(1, msrs, i);
        }
 
        /* enable active counters */
-       for (i = 0; i < NUM_COUNTERS; ++i) {
-               if ((counter_config[i].enabled) && (CTR_IS_RESERVED(msrs, i))) {
-                       reset_value[i] = counter_config[i].count;
-
-                       CTR_WRITE(counter_config[i].count, msrs, i);
+       for (i = 0; i < NUM_HARDWARE_COUNTERS; ++i) {
+               int offset = i + __get_cpu_var(switch_index);
+               if ((counter_config[offset].enabled) && (CTR_IS_RESERVED(msrs, i))) {
+                       CTR_WRITE(counter_config[offset].count, msrs, i);
 
                        CTRL_READ(low, high, msrs, i);
                        CTRL_CLEAR_LO(low);
                        CTRL_CLEAR_HI(high);
                        CTRL_SET_ENABLE(low);
-                       CTRL_SET_USR(low, counter_config[i].user);
-                       CTRL_SET_KERN(low, counter_config[i].kernel);
-                       CTRL_SET_UM(low, counter_config[i].unit_mask);
-                       CTRL_SET_EVENT_LOW(low, counter_config[i].event);
-                       CTRL_SET_EVENT_HIGH(high, counter_config[i].event);
+                       CTRL_SET_USR(low, counter_config[offset].user);
+                       CTRL_SET_KERN(low, counter_config[offset].kernel);
+                       CTRL_SET_UM(low, counter_config[offset].unit_mask);
+                       CTRL_SET_EVENT_LOW(low, counter_config[offset].event);
+                       CTRL_SET_EVENT_HIGH(high, counter_config[offset].event);
                        CTRL_SET_HOST_ONLY(high, 0);
                        CTRL_SET_GUEST_ONLY(high, 0);
 
                        CTRL_WRITE(low, high, msrs, i);
-               } else {
-                       reset_value[i] = 0;
                }
        }
 }
@@ -276,13 +287,14 @@ static int op_amd_check_ctrs(struct pt_regs * const regs,
        unsigned int low, high;
        int i;
 
-       for (i = 0 ; i < NUM_COUNTERS; ++i) {
-               if (!reset_value[i])
+       for (i = 0 ; i < NUM_HARDWARE_COUNTERS ; ++i) {
+               int offset = i + __get_cpu_var(switch_index);
+               if (!reset_value[offset])
                        continue;
                CTR_READ(low, high, msrs, i);
                if (CTR_OVERFLOWED(low)) {
-                       oprofile_add_sample(regs, i);
-                       CTR_WRITE(reset_value[i], msrs, i);
+                       oprofile_add_sample(regs, offset);
+                       CTR_WRITE(reset_value[offset], msrs, i);
                }
        }
 
@@ -298,8 +310,10 @@ static void op_amd_start(struct op_msrs const * const msrs)
 {
        unsigned int low, high;
        int i;
-       for (i = 0 ; i < NUM_COUNTERS ; ++i) {
-               if (reset_value[i]) {
+
+       for (i = 0 ; i < NUM_HARDWARE_COUNTERS ; ++i) {
+               int offset = i + __get_cpu_var(switch_index);
+               if (reset_value[offset]) {
                        CTRL_READ(low, high, msrs, i);
                        CTRL_SET_ACTIVE(low);
                        CTRL_WRITE(low, high, msrs, i);
@@ -329,8 +343,8 @@ static void op_amd_stop(struct op_msrs const * const msrs)
 
        /* Subtle: stop on all counters to avoid race with
         * setting our pm callback */
-       for (i = 0 ; i < NUM_COUNTERS ; ++i) {
-               if (!reset_value[i])
+       for (i = 0 ; i < NUM_HARDWARE_COUNTERS ; ++i) {
+               if (!reset_value[i + per_cpu(switch_index, smp_processor_id())])
                        continue;
                CTRL_READ(low, high, msrs, i);
                CTRL_SET_INACTIVE(low);
@@ -356,11 +370,11 @@ static void op_amd_shutdown(struct op_msrs const * const msrs)
 {
        int i;
 
-       for (i = 0 ; i < NUM_COUNTERS ; ++i) {
+       for (i = 0 ; i < NUM_HARDWARE_COUNTERS ; ++i) {
                if (CTR_IS_RESERVED(msrs, i))
                        release_perfctr_nmi(MSR_K7_PERFCTR0 + i);
        }
-       for (i = 0 ; i < NUM_CONTROLS ; ++i) {
+       for (i = 0 ; i < NUM_HARDWARE_COUNTERS ; ++i) {
                if (CTRL_IS_RESERVED(msrs, i))
                        release_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
        }
@@ -534,6 +548,8 @@ struct op_x86_model_spec const op_amd_spec = {
        .exit = op_amd_exit,
        .num_counters = NUM_COUNTERS,
        .num_controls = NUM_CONTROLS,
+       .num_hardware_counters = NUM_HARDWARE_COUNTERS,
+       .num_hardware_controls = NUM_HARDWARE_CONTROLS,
        .fill_in_addresses = &op_amd_fill_in_addresses,
        .setup_ctrs = &op_amd_setup_ctrs,
        .check_ctrs = &op_amd_check_ctrs,
index 56b4757..e641545 100644 (file)
@@ -701,6 +701,8 @@ static void p4_shutdown(struct op_msrs const * const msrs)
 struct op_x86_model_spec const op_p4_ht2_spec = {
        .num_counters = NUM_COUNTERS_HT2,
        .num_controls = NUM_CONTROLS_HT2,
+       .num_hardware_counters = NUM_COUNTERS_HT2,
+       .num_hardware_controls = NUM_CONTROLS_HT2,
        .fill_in_addresses = &p4_fill_in_addresses,
        .setup_ctrs = &p4_setup_ctrs,
        .check_ctrs = &p4_check_ctrs,
@@ -713,6 +715,8 @@ struct op_x86_model_spec const op_p4_ht2_spec = {
 struct op_x86_model_spec const op_p4_spec = {
        .num_counters = NUM_COUNTERS_NON_HT,
        .num_controls = NUM_CONTROLS_NON_HT,
+       .num_hardware_counters = NUM_COUNTERS_NON_HT,
+       .num_hardware_controls = NUM_CONTROLS_NON_HT,
        .fill_in_addresses = &p4_fill_in_addresses,
        .setup_ctrs = &p4_setup_ctrs,
        .check_ctrs = &p4_check_ctrs,
index eff431f..e5811aa 100644 (file)
@@ -183,6 +183,8 @@ static void ppro_shutdown(struct op_msrs const * const msrs)
 struct op_x86_model_spec const op_ppro_spec = {
        .num_counters = NUM_COUNTERS,
        .num_controls = NUM_CONTROLS,
+       .num_hardware_counters = NUM_COUNTERS,
+       .num_hardware_controls = NUM_CONTROLS,
        .fill_in_addresses = &ppro_fill_in_addresses,
        .setup_ctrs = &ppro_setup_ctrs,
        .check_ctrs = &ppro_check_ctrs,
index 05a0261..e07ba10 100644 (file)
@@ -19,6 +19,7 @@ struct op_saved_msr {
 struct op_msr {
        unsigned long addr;
        struct op_saved_msr saved;
+       struct op_saved_msr multiplex;
 };
 
 struct op_msrs {
@@ -34,6 +35,8 @@ struct pt_regs;
 struct op_x86_model_spec {
        int (*init)(struct oprofile_operations *ops);
        void (*exit)(void);
+       unsigned int const num_hardware_counters;
+       unsigned int const num_hardware_controls;
        unsigned int const num_counters;
        unsigned int const num_controls;
        void (*fill_in_addresses)(struct op_msrs * const msrs);
index 2c64517..b2fa5df 100644 (file)
@@ -12,6 +12,8 @@
 #include <linux/init.h>
 #include <linux/oprofile.h>
 #include <linux/moduleparam.h>
+#include <linux/workqueue.h>
+#include <linux/time.h>
 #include <asm/mutex.h>
 
 #include "oprof.h"
 #include "cpu_buffer.h"
 #include "buffer_sync.h"
 #include "oprofile_stats.h"
+
+static unsigned long is_setup;
+static void switch_worker(struct work_struct *work);
+static DECLARE_DELAYED_WORK(switch_work, switch_worker);
+static DEFINE_MUTEX(start_mutex);
  
 struct oprofile_operations oprofile_ops;
 
+unsigned long timeout_jiffies;
 unsigned long oprofile_started;
 unsigned long backtrace_depth;
-static unsigned long is_setup;
-static DEFINE_MUTEX(start_mutex);
+/* Multiplexing defaults at 1 msec*/
 
 /* timer
    0 - use performance monitoring hardware if available
@@ -87,6 +94,16 @@ out:
        return err;
 }
 
+static void start_switch_worker(void)
+{
+       schedule_delayed_work(&switch_work, timeout_jiffies);
+}
+
+static void switch_worker(struct work_struct *work)
+{
+       if (!oprofile_ops.switch_events())
+               start_switch_worker();
+}
 
 /* Actually start profiling (echo 1>/dev/oprofile/enable) */
 int oprofile_start(void)
@@ -94,7 +111,6 @@ int oprofile_start(void)
        int err = -EINVAL;
  
        mutex_lock(&start_mutex);
        if (!is_setup)
                goto out;
 
@@ -108,6 +124,9 @@ int oprofile_start(void)
        if ((err = oprofile_ops.start()))
                goto out;
 
+       if (oprofile_ops.switch_events)
+               start_switch_worker();
+
        oprofile_started = 1;
 out:
        mutex_unlock(&start_mutex);
@@ -123,6 +142,7 @@ void oprofile_stop(void)
                goto out;
        oprofile_ops.stop();
        oprofile_started = 0;
+       cancel_delayed_work_sync(&switch_work);
        /* wake up the daemon to read what remains */
        wake_up_buffer_waiter();
 out:
@@ -155,6 +175,32 @@ post_sync:
        mutex_unlock(&start_mutex);
 }
 
+/* User inputs in ms, converts to jiffies */
+int oprofile_set_timeout(unsigned long val_msec)
+{
+       int err = 0;
+
+       mutex_lock(&start_mutex);
+
+       if (oprofile_started) {
+               err = -EBUSY;
+               goto out;
+       }
+
+       if (!oprofile_ops.switch_events) {
+               err = -EINVAL;
+               goto out;
+       }
+
+       timeout_jiffies = msecs_to_jiffies(val_msec);
+       if (timeout_jiffies == MAX_JIFFY_OFFSET)
+               timeout_jiffies = msecs_to_jiffies(1);
+
+out:
+       mutex_unlock(&start_mutex);
+       return err;
+
+}
 
 int oprofile_set_backtrace(unsigned long val)
 {
@@ -179,10 +225,16 @@ out:
        return err;
 }
 
+static void __init oprofile_switch_timer_init(void)
+{
+       timeout_jiffies = msecs_to_jiffies(1);
+}
+
 static int __init oprofile_init(void)
 {
        int err;
 
+       oprofile_switch_timer_init();
        err = oprofile_arch_init(&oprofile_ops);
 
        if (err < 0 || timer) {
index 1832365..c4406a7 100644 (file)
@@ -27,7 +27,8 @@ extern unsigned long fs_buffer_watershed;
 extern struct oprofile_operations oprofile_ops;
 extern unsigned long oprofile_started;
 extern unsigned long backtrace_depth;
+extern unsigned long timeout_jiffies;
+
 struct super_block;
 struct dentry;
 
@@ -35,5 +36,6 @@ void oprofile_create_files(struct super_block * sb, struct dentry * root);
 void oprofile_timer_init(struct oprofile_operations * ops);
 
 int oprofile_set_backtrace(unsigned long depth);
+int oprofile_set_timeout(unsigned long time);
  
 #endif /* OPROF_H */
index ef953ba..cc4f5a1 100644 (file)
@@ -9,6 +9,7 @@
 
 #include <linux/fs.h>
 #include <linux/oprofile.h>
+#include <linux/jiffies.h>
 
 #include "event_buffer.h"
 #include "oprofile_stats.h"
@@ -18,6 +19,40 @@ unsigned long fs_buffer_size = 131072;
 unsigned long fs_cpu_buffer_size = 8192;
 unsigned long fs_buffer_watershed = 32768; /* FIXME: tune */
 
+static ssize_t timeout_read(struct file *file, char __user *buf,
+               size_t count, loff_t *offset)
+{
+       return oprofilefs_ulong_to_user(jiffies_to_msecs(timeout_jiffies),
+                               buf, count, offset);
+}
+
+
+static ssize_t timeout_write(struct file *file, char const __user *buf,
+               size_t count, loff_t *offset)
+{
+       unsigned long val;
+       int retval;
+
+       if (*offset)
+               return -EINVAL;
+
+       retval = oprofilefs_ulong_from_user(&val, buf, count);
+       if (retval)
+               return retval;
+
+       retval = oprofile_set_timeout(val);
+
+       if (retval)
+               return retval;
+       return count;
+}
+
+static const struct file_operations timeout_fops = {
+       .read           = timeout_read,
+       .write          = timeout_write,
+};
+
+
 static ssize_t depth_read(struct file * file, char __user * buf, size_t count, loff_t * offset)
 {
        return oprofilefs_ulong_to_user(backtrace_depth, buf, count, offset);
@@ -85,11 +120,10 @@ static ssize_t enable_write(struct file * file, char const __user * buf, size_t
 
        if (*offset)
                return -EINVAL;
-
        retval = oprofilefs_ulong_from_user(&val, buf, count);
        if (retval)
                return retval;
+
        if (val)
                retval = oprofile_start();
        else
@@ -129,6 +163,7 @@ void oprofile_create_files(struct super_block * sb, struct dentry * root)
        oprofilefs_create_file(sb, root, "cpu_type", &cpu_type_fops); 
        oprofilefs_create_file(sb, root, "backtrace_depth", &depth_fops);
        oprofilefs_create_file(sb, root, "pointer_size", &pointer_size_fops);
+       oprofilefs_create_file(sb, root, "timeout_ms", &timeout_fops);
        oprofile_create_stats_files(sb, root);
        if (oprofile_ops.create_files)
                oprofile_ops.create_files(sb, root);
index bcb8f72..687f2f4 100644 (file)
@@ -67,6 +67,9 @@ struct oprofile_operations {
 
        /* Initiate a stack backtrace. Optional. */
        void (*backtrace)(struct pt_regs * const regs, unsigned int depth);
+
+       /* Multiplex between different events. Optional. */
+       int (*switch_events)(void);
        /* CPU identification string. */
        char * cpu_type;
 };