From: Feng Tang <feng.tang@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H . Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>,
x86@kernel.org, linux-kernel@vger.kernel.org
Cc: rui.zhang@intel.com, andi.kleen@intel.com, dave.hansen@intel.com,
len.brown@intel.com, Feng Tang <feng.tang@intel.com>
Subject: [PATCH v2 1/2] x86/tsc: add a timer to make sure tsc_adjust is always checked
Date: Tue, 13 Apr 2021 13:31:36 +0800 [thread overview]
Message-ID: <1618291897-71581-1-git-send-email-feng.tang@intel.com> (raw)
Normally the tsc_sync will get checked every time system enters idle state,
but Thomas Gleixner mentioned there is still a caveat that a system won't
enter idle [1], either because it's too busy or configured purposely to not
enter idle. Setup a periodic timer to make sure the check is always on.
[1]. https://lore.kernel.org/lkml/875z286xtk.fsf@nanos.tec.linutronix.de/
Signed-off-by: Feng Tang <feng.tang@intel.com>
---
Change log:
v2:
* skip timer setup when tsc_clocksource_reliabe==1 (Thomas)
* refine comment and code format (Thomas)
arch/x86/kernel/tsc_sync.c | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index 3d3c761..39f18fa 100644
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -30,6 +30,7 @@ struct tsc_adjust {
};
static DEFINE_PER_CPU(struct tsc_adjust, tsc_adjust);
+static struct timer_list tsc_sync_check_timer;
/*
* TSC's on different sockets may be reset asynchronously.
@@ -77,6 +78,44 @@ void tsc_verify_tsc_adjust(bool resume)
}
}
+/*
+ * Normally the tsc_sync will be checked every time system enters idle state,
+ * but there is still caveat that a system won't enter idle, either because
+ * it's too busy or configured purposely to not enter idle.
+ *
+ * So setup a periodic timer to make sure the check is always on.
+ */
+
+#define SYNC_CHECK_INTERVAL (HZ * 600)
+
+static void tsc_sync_check_timer_fn(struct timer_list *unused)
+{
+ int next_cpu;
+
+ tsc_verify_tsc_adjust(false);
+
+ /* Run the check for all onlined CPUs in turn */
+ next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask);
+ if (next_cpu >= nr_cpu_ids)
+ next_cpu = cpumask_first(cpu_online_mask);
+
+ tsc_sync_check_timer.expires += SYNC_CHECK_INTERVAL;
+ add_timer_on(&tsc_sync_check_timer, next_cpu);
+}
+
+static int __init start_sync_check_timer(void)
+{
+ if (!boot_cpu_has(X86_FEATURE_TSC_ADJUST) || tsc_clocksource_reliable)
+ return 0;
+
+ timer_setup(&tsc_sync_check_timer, tsc_sync_check_timer_fn, 0);
+ tsc_sync_check_timer.expires = jiffies + SYNC_CHECK_INTERVAL;
+ add_timer(&tsc_sync_check_timer);
+
+ return 0;
+}
+late_initcall(start_sync_check_timer);
+
static void tsc_sanitize_first_cpu(struct tsc_adjust *cur, s64 bootval,
unsigned int cpu, bool bootcpu)
{
--
2.7.4
next reply other threads:[~2021-04-13 5:31 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-13 5:31 Feng Tang [this message]
2021-04-13 5:31 ` [PATCH v2 2/2] x86/tsc: skip tsc watchdog checking for qualified platforms Feng Tang
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