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ring-buffer: Add percentage of ring buffer full to wake up reader

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Instead of just waiting for a page to be full before waking up a pending
reader, allow the reader to pass in a "percentage" of pages that have
content before waking up a reader. This should help keep the process of
reading the events not cause wake ups that constantly cause reading of the
buffer.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware)
2018-11-29 20:32:26 -05:00
parent 9c8e2f6d3d
commit 2c2b0a78b3
3 changed files with 73 additions and 10 deletions
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8
kernel/trace/trace.c
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@@ -1431,7 +1431,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
}
#endif /* CONFIG_TRACER_MAX_TRACE */
static int wait_on_pipe(struct trace_iterator *iter, bool full)
static int wait_on_pipe(struct trace_iterator *iter, int full)
{
/* Iterators are static, they should be filled or empty */
if (trace_buffer_iter(iter, iter->cpu_file))
@@ -5693,7 +5693,7 @@ static int tracing_wait_pipe(struct file *filp)
mutex_unlock(&iter->mutex);
ret = wait_on_pipe(iter, false);
ret = wait_on_pipe(iter, 0);
mutex_lock(&iter->mutex);
@@ -6751,7 +6751,7 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
if ((filp->f_flags & O_NONBLOCK))
return -EAGAIN;
ret = wait_on_pipe(iter, false);
ret = wait_on_pipe(iter, 0);
if (ret)
return ret;
@@ -6948,7 +6948,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
if ((file->f_flags & O_NONBLOCK) || (flags & SPLICE_F_NONBLOCK))
goto out;
ret = wait_on_pipe(iter, true);
ret = wait_on_pipe(iter, 1);
if (ret)
goto out;