lkml.org 
[lkml]   [2021]   [Jun]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH V5 03/14] trace/hwlat: Switch disable_migrate to mode none
Date
When in the round-robin mode, if the tracer detects a change in the
hwlatd thread affinity by an external tool, e.g., taskset, the
round-robin logic is disabled. The disable_migrate variable currently
tracks this.

With the addition of the "mode" config and the mode "none," the
disable_migrate logic is equivalent to switch to the "none" mode.

Hence, instead of using a hidden variable to track this behavior,
switch the mode to none, informing the user about this change.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexandre Chartre <alexandre.chartre@oracle.com>
Cc: Clark Willaims <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
---
kernel/trace/trace_hwlat.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index 43a436d85a01..bae74b95cf55 100644
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -286,7 +286,6 @@ static int get_sample(void)
}

static struct cpumask save_cpumask;
-static bool disable_migrate;

static void move_to_next_cpu(void)
{
@@ -294,15 +293,13 @@ static void move_to_next_cpu(void)
struct trace_array *tr = hwlat_trace;
int next_cpu;

- if (disable_migrate)
- return;
/*
* If for some reason the user modifies the CPU affinity
* of this thread, then stop migrating for the duration
* of the current test.
*/
if (!cpumask_equal(current_mask, current->cpus_ptr))
- goto disable;
+ goto change_mode;

get_online_cpus();
cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask);
@@ -313,7 +310,7 @@ static void move_to_next_cpu(void)
next_cpu = cpumask_first(current_mask);

if (next_cpu >= nr_cpu_ids) /* Shouldn't happen! */
- goto disable;
+ goto change_mode;

cpumask_clear(current_mask);
cpumask_set_cpu(next_cpu, current_mask);
@@ -321,8 +318,9 @@ static void move_to_next_cpu(void)
sched_setaffinity(0, current_mask);
return;

- disable:
- disable_migrate = true;
+ change_mode:
+ hwlat_data.thread_mode = MODE_NONE;
+ pr_info(BANNER "cpumask changed while in round-robin mode, switching to mode none\n");
}

/*
@@ -744,7 +742,6 @@ static int hwlat_tracer_init(struct trace_array *tr)

hwlat_trace = tr;

- disable_migrate = false;
hwlat_data.count = 0;
tr->max_latency = 0;
save_tracing_thresh = tracing_thresh;
--
2.31.1
\
 
 \ /
  Last update: 2021-06-22 16:44    [W:0.111 / U:0.088 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site