[PATCH V5 03/14] trace/hwlat: Switch disable_migrate to mode none
From: Daniel Bristot de Oliveira <hidden>
Date: 2021-06-22 14:43:46
Also in:
lkml
Subsystem:
the rest, tracing, tracing os noise / latency tracers · Maintainers:
Linus Torvalds, Steven Rostedt, Masami Hiramatsu
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 <redacted> Cc: Alexandre Chartre <redacted> Cc: Clark Willaims <redacted> 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 <redacted> --- 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