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tracing: Add tracefs file buffer_percentage

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Add a "buffer_percentage" file, that allows users to specify how much of the
buffer (percentage of pages) need to be filled before waking up a task
blocked on a per cpu trace_pipe_raw file.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware) 2018-11-29 21:38:42 -05:00
parent 2c2b0a78b3
commit 03329f9939
3 changed files with 77 additions and 17 deletions
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39
kernel/trace/ring_buffer.c
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@ -489,6 +489,7 @@ struct ring_buffer_per_cpu {
local_t commits;
local_t pages_touched;
local_t pages_read;
long last_pages_touch;
size_t shortest_full;
unsigned long read;
unsigned long read_bytes;
@ -2632,7 +2633,9 @@ static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer,
static __always_inline void
rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer)
{
bool pagebusy;
size_t nr_pages;
size_t dirty;
size_t full;
if (buffer->irq_work.waiters_pending) {
buffer->irq_work.waiters_pending = false;
@ -2646,24 +2649,27 @@ rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer)
irq_work_queue(&cpu_buffer->irq_work.work);
}
pagebusy = cpu_buffer->reader_page == cpu_buffer->commit_page;
if (cpu_buffer->last_pages_touch == local_read(&cpu_buffer->pages_touched))
return;
if (!pagebusy && cpu_buffer->irq_work.full_waiters_pending) {
size_t nr_pages;
size_t dirty;
size_t full;
if (cpu_buffer->reader_page == cpu_buffer->commit_page)
return;
full = cpu_buffer->shortest_full;
nr_pages = cpu_buffer->nr_pages;
dirty = ring_buffer_nr_dirty_pages(buffer, cpu_buffer->cpu);
if (full && nr_pages && (dirty * 100) <= full * nr_pages)
return;
if (!cpu_buffer->irq_work.full_waiters_pending)
return;
cpu_buffer->irq_work.wakeup_full = true;
cpu_buffer->irq_work.full_waiters_pending = false;
/* irq_work_queue() supplies it's own memory barriers */
irq_work_queue(&cpu_buffer->irq_work.work);
}
cpu_buffer->last_pages_touch = local_read(&cpu_buffer->pages_touched);
full = cpu_buffer->shortest_full;
nr_pages = cpu_buffer->nr_pages;
dirty = ring_buffer_nr_dirty_pages(buffer, cpu_buffer->cpu);
if (full && nr_pages && (dirty * 100) <= full * nr_pages)
return;
cpu_buffer->irq_work.wakeup_full = true;
cpu_buffer->irq_work.full_waiters_pending = false;
/* irq_work_queue() supplies it's own memory barriers */
irq_work_queue(&cpu_buffer->irq_work.work);
}
/*
@ -4394,6 +4400,7 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer)
local_set(&cpu_buffer->commits, 0);
local_set(&cpu_buffer->pages_touched, 0);
local_set(&cpu_buffer->pages_read, 0);
cpu_buffer->last_pages_touch = 0;
cpu_buffer->shortest_full = 0;
cpu_buffer->read = 0;
cpu_buffer->read_bytes = 0;