perf, trace: Optimize tracepoints by removing IRQ-disable from perf/tracepoint intera...

[net-next-2.6.git] / kernel / trace / trace_event_perf.c

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 89b780a7c5224e514bd475c485dc261679608f58..a1304f8c4440d768d36648483e790bb0b56f2434 100644 (file)
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -9,13 +9,9 @@
 #include <linux/kprobes.h>
 #include "trace.h"
 
-DEFINE_PER_CPU(struct pt_regs, perf_trace_regs);
-EXPORT_PER_CPU_SYMBOL_GPL(perf_trace_regs);
-
 EXPORT_SYMBOL_GPL(perf_arch_fetch_caller_regs);
 
-static char *perf_trace_buf;
-static char *perf_trace_buf_nmi;
+static char *perf_trace_buf[4];
 
 /*
  * Force it to be aligned to unsigned long to avoid misaligned accesses
@@ -29,7 +25,6 @@ static int    total_ref_count;
 
 static int perf_trace_event_enable(struct ftrace_event_call *event, void *data)
 {
-       char *buf;
        int ret = -ENOMEM;
 
        if (event->perf_refcount++ > 0) {
@@ -38,17 +33,16 @@ static int perf_trace_event_enable(struct ftrace_event_call *event, void *data)
        }
 
        if (!total_ref_count) {
-               buf = (char *)alloc_percpu(perf_trace_t);
-               if (!buf)
-                       goto fail_buf;
-
-               rcu_assign_pointer(perf_trace_buf, buf);
+               char *buf;
+               int i;
 
-               buf = (char *)alloc_percpu(perf_trace_t);
-               if (!buf)
-                       goto fail_buf_nmi;
+               for (i = 0; i < 4; i++) {
+                       buf = (char *)alloc_percpu(perf_trace_t);
+                       if (!buf)
+                               goto fail_buf;
 
-               rcu_assign_pointer(perf_trace_buf_nmi, buf);
+                       rcu_assign_pointer(perf_trace_buf[i], buf);
+               }
        }
 
        ret = event->perf_event_enable(event);
@@ -58,14 +52,15 @@ static int perf_trace_event_enable(struct ftrace_event_call *event, void *data)
                return 0;
        }
 
-fail_buf_nmi:
+fail_buf:
        if (!total_ref_count) {
-               free_percpu(perf_trace_buf_nmi);
-               free_percpu(perf_trace_buf);
-               perf_trace_buf_nmi = NULL;
-               perf_trace_buf = NULL;
+               int i;
+
+               for (i = 0; i < 4; i++) {
+                       free_percpu(perf_trace_buf[i]);
+                       perf_trace_buf[i] = NULL;
+               }
        }
-fail_buf:
        event->perf_refcount--;
 
        return ret;
@@ -91,19 +86,19 @@ int perf_trace_enable(int event_id, void *data)
 
 static void perf_trace_event_disable(struct ftrace_event_call *event)
 {
-       char *buf, *nmi_buf;
-
        if (--event->perf_refcount > 0)
                return;
 
        event->perf_event_disable(event);
 
        if (!--total_ref_count) {
-               buf = perf_trace_buf;
-               rcu_assign_pointer(perf_trace_buf, NULL);
+               char *buf[4];
+               int i;
 
-               nmi_buf = perf_trace_buf_nmi;
-               rcu_assign_pointer(perf_trace_buf_nmi, NULL);
+               for (i = 0; i < 4; i++) {
+                       buf[i] = perf_trace_buf[i];
+                       rcu_assign_pointer(perf_trace_buf[i], NULL);
+               }
 
                /*
                 * Ensure every events in profiling have finished before
@@ -111,8 +106,8 @@ static void perf_trace_event_disable(struct ftrace_event_call *event)
                 */
                synchronize_sched();
 
-               free_percpu(buf);
-               free_percpu(nmi_buf);
+               for (i = 0; i < 4; i++)
+                       free_percpu(buf[i]);
        }
 }
 
@@ -132,47 +127,37 @@ void perf_trace_disable(int event_id)
 }
 
 __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
-                                      int *rctxp, unsigned long *irq_flags)
+                                      struct pt_regs *regs, int *rctxp)
 {
        struct trace_entry *entry;
        char *trace_buf, *raw_data;
-       int pc, cpu;
+       int pc;
 
        BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
 
        pc = preempt_count();
 
-       /* Protect the per cpu buffer, begin the rcu read side */
-       local_irq_save(*irq_flags);
-
        *rctxp = perf_swevent_get_recursion_context();
        if (*rctxp < 0)
                goto err_recursion;
 
-       cpu = smp_processor_id();
-
-       if (in_nmi())
-               trace_buf = rcu_dereference_sched(perf_trace_buf_nmi);
-       else
-               trace_buf = rcu_dereference_sched(perf_trace_buf);
-
+       trace_buf = rcu_dereference_sched(perf_trace_buf[*rctxp]);
        if (!trace_buf)
                goto err;
 
-       raw_data = per_cpu_ptr(trace_buf, cpu);
+       raw_data = per_cpu_ptr(trace_buf, smp_processor_id());
 
        /* zero the dead bytes from align to not leak stack to user */
        memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
 
        entry = (struct trace_entry *)raw_data;
-       tracing_generic_entry_update(entry, *irq_flags, pc);
+       tracing_generic_entry_update(entry, regs->flags, pc);
        entry->type = type;
 
        return raw_data;
 err:
        perf_swevent_put_recursion_context(*rctxp);
 err_recursion:
-       local_irq_restore(*irq_flags);
        return NULL;
 }
 EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);