x86, perf_counter, bts: Optimize BTS overflow handling

Draining the BTS buffer on a buffer overflow interrupt takes too
long resulting in a kernel lockup when tracing the kernel.

Restructure perf_counter sampling into sample creation and sample
output.

Prepare a single reference sample for BTS sampling and update the
from and to address fields when draining the BTS buffer. Drain the
entire BTS buffer between a single perf_output_begin() /
perf_output_end() pair.

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090915130023.A16204@sedona.ch.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 64 insertions, 4 deletions

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 6c1ef72ea501..c7375f97aa19 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -691,6 +691,17 @@ struct perf_cpu_context {
         int                             recursion[4];
 };
 
+struct perf_output_handle {
+        struct perf_counter     *counter;
+        struct perf_mmap_data   *data;
+        unsigned long           head;
+        unsigned long           offset;
+        int                     nmi;
+        int                     sample;
+        int                     locked;
+        unsigned long           flags;
+};
+
 #ifdef CONFIG_PERF_COUNTERS
 
 /*
@@ -722,16 +733,38 @@ extern int hw_perf_group_sched_in(struct perf_counter *group_leader,
 extern void perf_counter_update_userpage(struct perf_counter *counter);
 
 struct perf_sample_data {
-        struct pt_regs                  *regs;
+        u64                             type;
+
+        u64                             ip;
+        struct {
+                u32     pid;
+                u32     tid;
+        }                               tid_entry;
+        u64                             time;
         u64                             addr;
+        u64                             id;
+        u64                             stream_id;
+        struct {
+                u32     cpu;
+                u32     reserved;
+        }                               cpu_entry;
         u64                             period;
+        struct perf_callchain_entry     *callchain;
         struct perf_raw_record          *raw;
 };
 
+extern void perf_output_sample(struct perf_output_handle *handle,
+                               struct perf_event_header *header,
+                               struct perf_sample_data *data,
+                               struct perf_counter *counter);
+extern void perf_prepare_sample(struct perf_event_header *header,
+                                struct perf_sample_data *data,
+                                struct perf_counter *counter,
+                                struct pt_regs *regs);
+
 extern int perf_counter_overflow(struct perf_counter *counter, int nmi,
-                                 struct perf_sample_data *data);
-extern void perf_counter_output(struct perf_counter *counter, int nmi,
-                                struct perf_sample_data *data);
+                                 struct perf_sample_data *data,
+                                 struct pt_regs *regs);
 
 /*
  * Return 1 for a software counter, 0 for a hardware counter
@@ -781,6 +814,12 @@ extern void perf_tpcounter_event(int event_id, u64 addr, u64 count,
 #define perf_instruction_pointer(regs)  instruction_pointer(regs)
 #endif
 
+extern int perf_output_begin(struct perf_output_handle *handle,
+                             struct perf_counter *counter, unsigned int size,
+                             int nmi, int sample);
+extern void perf_output_end(struct perf_output_handle *handle);
+extern void perf_output_copy(struct perf_output_handle *handle,
+                             const void *buf, unsigned int len);
 #else
 static inline void
 perf_counter_task_sched_in(struct task_struct *task, int cpu)           { }
@@ -807,7 +846,28 @@ static inline void perf_counter_mmap(struct vm_area_struct *vma)	{ }
 static inline void perf_counter_comm(struct task_struct *tsk)           { }
 static inline void perf_counter_fork(struct task_struct *tsk)           { }
 static inline void perf_counter_init(void)                              { }
+
+static inline int
+perf_output_begin(struct perf_output_handle *handle, struct perf_counter *c,
+                  unsigned int size, int nmi, int sample)               { }
+static inline void perf_output_end(struct perf_output_handle *handle)   { }
+static inline void
+perf_output_copy(struct perf_output_handle *handle,
+                 const void *buf, unsigned int len)                     { }
+static inline void
+perf_output_sample(struct perf_output_handle *handle,
+                   struct perf_event_header *header,
+                   struct perf_sample_data *data,
+                   struct perf_counter *counter)                        { }
+static inline void
+perf_prepare_sample(struct perf_event_header *header,
+                    struct perf_sample_data *data,
+                    struct perf_counter *counter,
+                    struct pt_regs *regs)                               { }
 #endif
 
+#define perf_output_put(handle, x) \
+        perf_output_copy((handle), &(x), sizeof(x))
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_PERF_COUNTER_H */