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authorRobert Richter <robert.richter@amd.com>2008-12-25 17:26:07 +0100
committerRobert Richter <robert.richter@amd.com>2009-01-07 22:40:47 +0100
commitae735e9964b4584923f2997d98a8d80ae9c1a75c (patch)
tree0fc72d18bcc5951f9dd519e8a4527593724b816f /drivers/oprofile/cpu_buffer.c
parent2d87b14cf8d0b07720de26d90789d02124141616 (diff)
oprofile: rework implementation of cpu buffer events
Special events such as task or context switches are marked with an escape code in the cpu buffer followed by an event code or a task identifier. There is one escape code per event. To make escape sequences also available for data samples the internal cpu buffer format must be changed. The current implementation does not allow the extension of event codes since this would lead to collisions with the task identifiers. To avoid this, this patch introduces an event mask that allows the storage of multiple events with one escape code. Now, task identifiers are stored in the data section of the sample. The implementation also allows the usage of custom data in a sample. As a side effect the new code is much more readable and easier to understand. Signed-off-by: Robert Richter <robert.richter@amd.com>
Diffstat (limited to 'drivers/oprofile/cpu_buffer.c')
-rw-r--r--drivers/oprofile/cpu_buffer.c139
1 files changed, 75 insertions, 64 deletions
diff --git a/drivers/oprofile/cpu_buffer.c b/drivers/oprofile/cpu_buffer.c
index 400f7fcffdbe..e859d23cfc57 100644
--- a/drivers/oprofile/cpu_buffer.c
+++ b/drivers/oprofile/cpu_buffer.c
@@ -212,6 +212,59 @@ unsigned long op_cpu_buffer_entries(int cpu)
+ ring_buffer_entries_cpu(op_ring_buffer_write, cpu);
}
+static int
+op_add_code(struct oprofile_cpu_buffer *cpu_buf, unsigned long backtrace,
+ int is_kernel, struct task_struct *task)
+{
+ struct op_entry entry;
+ struct op_sample *sample;
+ unsigned long flags;
+ int size;
+
+ flags = 0;
+
+ if (backtrace)
+ flags |= TRACE_BEGIN;
+
+ /* notice a switch from user->kernel or vice versa */
+ is_kernel = !!is_kernel;
+ if (cpu_buf->last_is_kernel != is_kernel) {
+ cpu_buf->last_is_kernel = is_kernel;
+ flags |= KERNEL_CTX_SWITCH;
+ if (is_kernel)
+ flags |= IS_KERNEL;
+ }
+
+ /* notice a task switch */
+ if (cpu_buf->last_task != task) {
+ cpu_buf->last_task = task;
+ flags |= USER_CTX_SWITCH;
+ }
+
+ if (!flags)
+ /* nothing to do */
+ return 0;
+
+ if (flags & USER_CTX_SWITCH)
+ size = 1;
+ else
+ size = 0;
+
+ sample = op_cpu_buffer_write_reserve(&entry, size);
+ if (!sample)
+ return -ENOMEM;
+
+ sample->eip = ESCAPE_CODE;
+ sample->event = flags;
+
+ if (size)
+ sample->data[0] = (unsigned long)task;
+
+ op_cpu_buffer_write_commit(&entry);
+
+ return 0;
+}
+
static inline int
op_add_sample(struct oprofile_cpu_buffer *cpu_buf,
unsigned long pc, unsigned long event)
@@ -229,26 +282,18 @@ op_add_sample(struct oprofile_cpu_buffer *cpu_buf,
return op_cpu_buffer_write_commit(&entry);
}
-static inline int
-add_code(struct oprofile_cpu_buffer *buffer, unsigned long value)
-{
- return op_add_sample(buffer, ESCAPE_CODE, value);
-}
-
-/* This must be safe from any context. It's safe writing here
- * because of the head/tail separation of the writer and reader
- * of the CPU buffer.
+/*
+ * This must be safe from any context.
*
* is_kernel is needed because on some architectures you cannot
* tell if you are in kernel or user space simply by looking at
* pc. We tag this in the buffer by generating kernel enter/exit
* events whenever is_kernel changes
*/
-static int log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc,
- int is_kernel, unsigned long event)
+static int
+log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc,
+ unsigned long backtrace, int is_kernel, unsigned long event)
{
- struct task_struct *task;
-
cpu_buf->sample_received++;
if (pc == ESCAPE_CODE) {
@@ -256,23 +301,8 @@ static int log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc,
return 0;
}
- is_kernel = !!is_kernel;
-
- task = current;
-
- /* notice a switch from user->kernel or vice versa */
- if (cpu_buf->last_is_kernel != is_kernel) {
- cpu_buf->last_is_kernel = is_kernel;
- if (add_code(cpu_buf, is_kernel))
- goto fail;
- }
-
- /* notice a task switch */
- if (cpu_buf->last_task != task) {
- cpu_buf->last_task = task;
- if (add_code(cpu_buf, (unsigned long)task))
- goto fail;
- }
+ if (op_add_code(cpu_buf, backtrace, is_kernel, current))
+ goto fail;
if (op_add_sample(cpu_buf, pc, event))
goto fail;
@@ -286,7 +316,6 @@ fail:
static inline void oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf)
{
- add_code(cpu_buf, CPU_TRACE_BEGIN);
cpu_buf->tracing = 1;
}
@@ -300,21 +329,21 @@ __oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,
unsigned long event, int is_kernel)
{
struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
-
- if (!oprofile_backtrace_depth) {
- log_sample(cpu_buf, pc, is_kernel, event);
- return;
- }
-
- oprofile_begin_trace(cpu_buf);
+ unsigned long backtrace = oprofile_backtrace_depth;
/*
* if log_sample() fail we can't backtrace since we lost the
* source of this event
*/
- if (log_sample(cpu_buf, pc, is_kernel, event))
- oprofile_ops.backtrace(regs, oprofile_backtrace_depth);
+ if (!log_sample(cpu_buf, pc, backtrace, is_kernel, event))
+ /* failed */
+ return;
+ if (!backtrace)
+ return;
+
+ oprofile_begin_trace(cpu_buf);
+ oprofile_ops.backtrace(regs, backtrace);
oprofile_end_trace(cpu_buf);
}
@@ -339,29 +368,14 @@ void oprofile_add_ibs_sample(struct pt_regs * const regs,
{
int is_kernel = !user_mode(regs);
struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
- struct task_struct *task;
int fail = 0;
cpu_buf->sample_received++;
- /* notice a switch from user->kernel or vice versa */
- if (cpu_buf->last_is_kernel != is_kernel) {
- if (add_code(cpu_buf, is_kernel))
- goto fail;
- cpu_buf->last_is_kernel = is_kernel;
- }
+ /* backtraces disabled for ibs */
+ fail = fail || op_add_code(cpu_buf, 0, is_kernel, current);
- /* notice a task switch */
- if (!is_kernel) {
- task = current;
- if (cpu_buf->last_task != task) {
- if (add_code(cpu_buf, (unsigned long)task))
- goto fail;
- cpu_buf->last_task = task;
- }
- }
-
- fail = fail || add_code(cpu_buf, ibs_code);
+ fail = fail || op_add_sample(cpu_buf, ESCAPE_CODE, ibs_code);
fail = fail || op_add_sample(cpu_buf, ibs_sample[0], ibs_sample[1]);
fail = fail || op_add_sample(cpu_buf, ibs_sample[2], ibs_sample[3]);
fail = fail || op_add_sample(cpu_buf, ibs_sample[4], ibs_sample[5]);
@@ -372,11 +386,8 @@ void oprofile_add_ibs_sample(struct pt_regs * const regs,
fail = fail || op_add_sample(cpu_buf, ibs_sample[10], ibs_sample[11]);
}
- if (!fail)
- return;
-
-fail:
- cpu_buf->sample_lost_overflow++;
+ if (fail)
+ cpu_buf->sample_lost_overflow++;
}
#endif
@@ -384,7 +395,7 @@ fail:
void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event)
{
struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
- log_sample(cpu_buf, pc, is_kernel, event);
+ log_sample(cpu_buf, pc, 0, is_kernel, event);
}
void oprofile_add_trace(unsigned long pc)