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author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2018-11-29 21:38:42 -0500 |
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committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2018-12-08 20:54:08 -0500 |
commit | 03329f9939781041424edd29487b9603a704fcd9 (patch) | |
tree | 4c6966726e5760072c97bedd0c16493bcf29109b /kernel/trace/trace.c | |
parent | 2c2b0a78b373908926e4683ea5571332f63c0eb5 (diff) | |
download | linux-stable-03329f9939781041424edd29487b9603a704fcd9.tar.gz linux-stable-03329f9939781041424edd29487b9603a704fcd9.tar.bz2 linux-stable-03329f9939781041424edd29487b9603a704fcd9.zip |
tracing: Add tracefs file buffer_percentage
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>
Diffstat (limited to 'kernel/trace/trace.c')
-rw-r--r-- | kernel/trace/trace.c | 54 |
1 files changed, 53 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 48d5eb22ff33..d382fd1aa4a6 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -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, 1); + ret = wait_on_pipe(iter, iter->tr->buffer_percent); if (ret) goto out; @@ -7662,6 +7662,53 @@ static const struct file_operations rb_simple_fops = { .llseek = default_llseek, }; +static ssize_t +buffer_percent_read(struct file *filp, char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + struct trace_array *tr = filp->private_data; + char buf[64]; + int r; + + r = tr->buffer_percent; + r = sprintf(buf, "%d\n", r); + + return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); +} + +static ssize_t +buffer_percent_write(struct file *filp, const char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + struct trace_array *tr = filp->private_data; + unsigned long val; + int ret; + + ret = kstrtoul_from_user(ubuf, cnt, 10, &val); + if (ret) + return ret; + + if (val > 100) + return -EINVAL; + + if (!val) + val = 1; + + tr->buffer_percent = val; + + (*ppos)++; + + return cnt; +} + +static const struct file_operations buffer_percent_fops = { + .open = tracing_open_generic_tr, + .read = buffer_percent_read, + .write = buffer_percent_write, + .release = tracing_release_generic_tr, + .llseek = default_llseek, +}; + struct dentry *trace_instance_dir; static void @@ -7970,6 +8017,11 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer) trace_create_file("timestamp_mode", 0444, d_tracer, tr, &trace_time_stamp_mode_fops); + tr->buffer_percent = 1; + + trace_create_file("buffer_percent", 0444, d_tracer, + tr, &buffer_percent_fops); + create_trace_options_dir(tr); #if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) |