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ring-buffer: Add event descriptor to simplify passing data

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Add rb_event_info descriptor to pass event info to functions a bit
easier than using a bunch of parameters. This will also allow for
changing the code around a bit to find better fast paths.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Red Hat) 2015-05-28 17:13:14 -04:00 committed by Steven Rostedt
parent 5e2d5ef8ec
commit fcc742eaad
1 changed files with 52 additions and 39 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

91
kernel/trace/ring_buffer.c
View file

@ -399,6 +399,17 @@ struct rb_irq_work {
bool wakeup_full; bool wakeup_full;
}; };
/*
* Structure to hold event state and handle nested events.
*/
struct rb_event_info {
u64 ts;
u64 delta;
unsigned long length;
struct buffer_page *tail_page;
int add_timestamp;
};
/* /*
* Used for which event context the event is in. * Used for which event context the event is in.
* NMI = 0 * NMI = 0
@ -2000,9 +2011,12 @@ rb_add_time_stamp(struct ring_buffer_event *event, u64 delta)
*/ */
static void static void
rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, rb_update_event(struct ring_buffer_per_cpu *cpu_buffer,
struct ring_buffer_event *event, unsigned length, struct ring_buffer_event *event,
int add_timestamp, u64 delta) struct rb_event_info *info)
{ {
unsigned length = info->length;
u64 delta = info->delta;
/* Only a commit updates the timestamp */ /* Only a commit updates the timestamp */
if (unlikely(!rb_event_is_commit(cpu_buffer, event))) if (unlikely(!rb_event_is_commit(cpu_buffer, event)))
delta = 0; delta = 0;
@ -2011,7 +2025,7 @@ rb_update_event(struct ring_buffer_per_cpu *cpu_buffer,
* If we need to add a timestamp, then we * If we need to add a timestamp, then we
* add it to the start of the resevered space. * add it to the start of the resevered space.
*/ */
if (unlikely(add_timestamp)) { if (unlikely(info->add_timestamp)) {
event = rb_add_time_stamp(event, delta); event = rb_add_time_stamp(event, delta);
length -= RB_LEN_TIME_EXTEND; length -= RB_LEN_TIME_EXTEND;
delta = 0; delta = 0;
@ -2203,10 +2217,11 @@ static unsigned rb_calculate_event_length(unsigned length)
static inline void static inline void
rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer,
struct buffer_page *tail_page, unsigned long tail, struct rb_event_info *info)
unsigned long tail, unsigned long length)
{ {
struct buffer_page *tail_page = info->tail_page;
struct ring_buffer_event *event; struct ring_buffer_event *event;
unsigned long length = info->length;
/* /*
* Only the event that crossed the page boundary * Only the event that crossed the page boundary
@ -2276,13 +2291,14 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer,
*/ */
static noinline struct ring_buffer_event * static noinline struct ring_buffer_event *
rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
unsigned long length, unsigned long tail, unsigned long tail, struct rb_event_info *info)
struct buffer_page *tail_page, u64 ts)
{ {
struct buffer_page *tail_page = info->tail_page;
struct buffer_page *commit_page = cpu_buffer->commit_page; struct buffer_page *commit_page = cpu_buffer->commit_page;
struct ring_buffer *buffer = cpu_buffer->buffer; struct ring_buffer *buffer = cpu_buffer->buffer;
struct buffer_page *next_page; struct buffer_page *next_page;
int ret; int ret;
u64 ts;
next_page = tail_page; next_page = tail_page;
@ -2368,25 +2384,24 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
out_again: out_again:
rb_reset_tail(cpu_buffer, tail_page, tail, length); rb_reset_tail(cpu_buffer, tail, info);
/* fail and let the caller try again */ /* fail and let the caller try again */
return ERR_PTR(-EAGAIN); return ERR_PTR(-EAGAIN);
out_reset: out_reset:
/* reset write */ /* reset write */
rb_reset_tail(cpu_buffer, tail_page, tail, length); rb_reset_tail(cpu_buffer, tail, info);
return NULL; return NULL;
} }
static struct ring_buffer_event * static struct ring_buffer_event *
__rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
unsigned long length, u64 ts, struct rb_event_info *info)
u64 delta, int add_timestamp)
{ {
struct buffer_page *tail_page;
struct ring_buffer_event *event; struct ring_buffer_event *event;
struct buffer_page *tail_page;
unsigned long tail, write; unsigned long tail, write;
/* /*
@ -2394,33 +2409,32 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
* hold in the time field of the event, then we append a * hold in the time field of the event, then we append a
* TIME EXTEND event ahead of the data event. * TIME EXTEND event ahead of the data event.
*/ */
if (unlikely(add_timestamp)) if (unlikely(info->add_timestamp))
length += RB_LEN_TIME_EXTEND; info->length += RB_LEN_TIME_EXTEND;
tail_page = cpu_buffer->tail_page; tail_page = info->tail_page = cpu_buffer->tail_page;
write = local_add_return(length, &tail_page->write); write = local_add_return(info->length, &tail_page->write);
/* set write to only the index of the write */ /* set write to only the index of the write */
write &= RB_WRITE_MASK; write &= RB_WRITE_MASK;
tail = write - length; tail = write - info->length;
/* /*
* If this is the first commit on the page, then it has the same * If this is the first commit on the page, then it has the same
* timestamp as the page itself. * timestamp as the page itself.
*/ */
if (!tail) if (!tail)
delta = 0; info->delta = 0;
/* See if we shot pass the end of this buffer page */ /* See if we shot pass the end of this buffer page */
if (unlikely(write > BUF_PAGE_SIZE)) if (unlikely(write > BUF_PAGE_SIZE))
return rb_move_tail(cpu_buffer, length, tail, return rb_move_tail(cpu_buffer, tail, info);
tail_page, ts);
/* We reserved something on the buffer */ /* We reserved something on the buffer */
event = __rb_page_index(tail_page, tail); event = __rb_page_index(tail_page, tail);
kmemcheck_annotate_bitfield(event, bitfield); kmemcheck_annotate_bitfield(event, bitfield);
rb_update_event(cpu_buffer, event, length, add_timestamp, delta); rb_update_event(cpu_buffer, event, info);
local_inc(&tail_page->entries); local_inc(&tail_page->entries);
@ -2429,10 +2443,10 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
* its timestamp. * its timestamp.
*/ */
if (!tail) if (!tail)
tail_page->page->time_stamp = ts; tail_page->page->time_stamp = info->ts;
/* account for these added bytes */ /* account for these added bytes */
local_add(length, &cpu_buffer->entries_bytes); local_add(info->length, &cpu_buffer->entries_bytes);
return event; return event;
} }
@ -2521,9 +2535,8 @@ rb_reserve_next_event(struct ring_buffer *buffer,
unsigned long length) unsigned long length)
{ {
struct ring_buffer_event *event; struct ring_buffer_event *event;
u64 ts, delta; struct rb_event_info info;
int nr_loops = 0; int nr_loops = 0;
int add_timestamp;
u64 diff; u64 diff;
rb_start_commit(cpu_buffer); rb_start_commit(cpu_buffer);
@ -2543,10 +2556,10 @@ rb_reserve_next_event(struct ring_buffer *buffer,
} }
#endif #endif
length = rb_calculate_event_length(length); info.length = rb_calculate_event_length(length);
again: again:
add_timestamp = 0; info.add_timestamp = 0;
delta = 0; info.delta = 0;
/* /*
* We allow for interrupts to reenter here and do a trace. * We allow for interrupts to reenter here and do a trace.
@ -2560,35 +2573,35 @@ rb_reserve_next_event(struct ring_buffer *buffer,
if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000))
goto out_fail; goto out_fail;
ts = rb_time_stamp(cpu_buffer->buffer); info.ts = rb_time_stamp(cpu_buffer->buffer);
diff = ts - cpu_buffer->write_stamp; diff = info.ts - cpu_buffer->write_stamp;
/* make sure this diff is calculated here */ /* make sure this diff is calculated here */
barrier(); barrier();
/* Did the write stamp get updated already? */ /* Did the write stamp get updated already? */
if (likely(ts >= cpu_buffer->write_stamp)) { if (likely(info.ts >= cpu_buffer->write_stamp)) {
delta = diff; info.delta = diff;
if (unlikely(test_time_stamp(delta))) { if (unlikely(test_time_stamp(info.delta))) {
int local_clock_stable = 1; int local_clock_stable = 1;
#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
local_clock_stable = sched_clock_stable(); local_clock_stable = sched_clock_stable();
#endif #endif
WARN_ONCE(delta > (1ULL << 59), WARN_ONCE(info.delta > (1ULL << 59),
KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s", KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s",
(unsigned long long)delta, (unsigned long long)info.delta,
(unsigned long long)ts, (unsigned long long)info.ts,
(unsigned long long)cpu_buffer->write_stamp, (unsigned long long)cpu_buffer->write_stamp,
local_clock_stable ? "" : local_clock_stable ? "" :
"If you just came from a suspend/resume,\n" "If you just came from a suspend/resume,\n"
"please switch to the trace global clock:\n" "please switch to the trace global clock:\n"
" echo global > /sys/kernel/debug/tracing/trace_clock\n"); " echo global > /sys/kernel/debug/tracing/trace_clock\n");
add_timestamp = 1; info.add_timestamp = 1;
} }
} }
event = __rb_reserve_next(cpu_buffer, length, ts, event = __rb_reserve_next(cpu_buffer, &info);
delta, add_timestamp);
if (unlikely(PTR_ERR(event) == -EAGAIN)) if (unlikely(PTR_ERR(event) == -EAGAIN))
goto again; goto again;