From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, "Paul E. McKenney" <paulmck@kernel.org>,
Andy Lutomirski <luto@kernel.org>,
Alexandre Chartre <alexandre.chartre@oracle.com>,
Frederic Weisbecker <frederic@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Petr Mladek <pmladek@suse.com>,
Steven Rostedt <rostedt@goodmis.org>,
Joel Fernandes <joel@joelfernandes.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>, Brian Gerst <brgerst@gmail.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Will Deacon <will@kernel.org>,
Tom Lendacky <thomas.lendacky@amd.com>,
Wei Liu <wei.liu@kernel.org>,
Michael Kelley <mikelley@microsoft.com>,
Jason Chen CJ <jason.cj.chen@intel.com>,
Zhao Yakui <yakui.zhao@intel.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>
Subject: [patch V6 01/37] tracing/hwlat: Use ktime_get_mono_fast_ns()
Date: Sat, 16 May 2020 01:45:48 +0200 [thread overview]
Message-ID: <20200515235124.466962628@linutronix.de> (raw)
In-Reply-To: 20200515234547.710474468@linutronix.de
Timestamping in the hardware latency detector uses sched_clock() underneath
and depends on CONFIG_GENERIC_SCHED_CLOCK=n because sched clocks from that
subsystem are not NMI safe.
ktime_get_mono_fast_ns() is NMI safe and available on all architectures.
Replace the time getter, get rid of the CONFIG_GENERIC_SCHED_CLOCK=n
dependency and cleanup the horrible macro maze which encapsulates u64 math
in u64 macros.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/trace/trace_hwlat.c | 59 +++++++++++++++++++--------------------------
1 file changed, 25 insertions(+), 34 deletions(-)
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -131,29 +131,19 @@ static void trace_hwlat_sample(struct hw
trace_buffer_unlock_commit_nostack(buffer, event);
}
-/* Macros to encapsulate the time capturing infrastructure */
-#define time_type u64
-#define time_get() trace_clock_local()
-#define time_to_us(x) div_u64(x, 1000)
-#define time_sub(a, b) ((a) - (b))
-#define init_time(a, b) (a = b)
-#define time_u64(a) a
-
+/*
+ * Timestamping uses ktime_get_mono_fast(), the NMI safe access to
+ * CLOCK_MONOTONIC.
+ */
void trace_hwlat_callback(bool enter)
{
if (smp_processor_id() != nmi_cpu)
return;
- /*
- * Currently trace_clock_local() calls sched_clock() and the
- * generic version is not NMI safe.
- */
- if (!IS_ENABLED(CONFIG_GENERIC_SCHED_CLOCK)) {
- if (enter)
- nmi_ts_start = time_get();
- else
- nmi_total_ts += time_get() - nmi_ts_start;
- }
+ if (enter)
+ nmi_ts_start = ktime_get_mono_fast_ns();
+ else
+ nmi_total_ts += ktime_get_mono_fast_ns() - nmi_ts_start;
if (enter)
nmi_count++;
@@ -165,20 +155,22 @@ void trace_hwlat_callback(bool enter)
* Used to repeatedly capture the CPU TSC (or similar), looking for potential
* hardware-induced latency. Called with interrupts disabled and with
* hwlat_data.lock held.
+ *
+ * Use ktime_get_mono_fast() here as well because it does not wait on the
+ * timekeeping seqcount like ktime_get_mono().
*/
static int get_sample(void)
{
struct trace_array *tr = hwlat_trace;
struct hwlat_sample s;
- time_type start, t1, t2, last_t2;
+ u64 start, t1, t2, last_t2, thresh;
s64 diff, outer_diff, total, last_total = 0;
u64 sample = 0;
- u64 thresh = tracing_thresh;
u64 outer_sample = 0;
int ret = -1;
unsigned int count = 0;
- do_div(thresh, NSEC_PER_USEC); /* modifies interval value */
+ thresh = div_u64(tracing_thresh, NSEC_PER_USEC);
nmi_cpu = smp_processor_id();
nmi_total_ts = 0;
@@ -188,18 +180,20 @@ static int get_sample(void)
trace_hwlat_callback_enabled = true;
- init_time(last_t2, 0);
- start = time_get(); /* start timestamp */
+ /* start timestamp */
+ start = ktime_get_mono_fast_ns();
outer_diff = 0;
+ last_t2 = 0;
do {
- t1 = time_get(); /* we'll look for a discontinuity */
- t2 = time_get();
+ /* we'll look for a discontinuity */
+ t1 = ktime_get_mono_fast_ns();
+ t2 = ktime_get_mono_fast_ns();
- if (time_u64(last_t2)) {
+ if (last_t2) {
/* Check the delta from outer loop (t2 to next t1) */
- outer_diff = time_to_us(time_sub(t1, last_t2));
+ outer_diff = div_u64(t1 - last_t2, NSEC_PER_USEC);
/* This shouldn't happen */
if (outer_diff < 0) {
pr_err(BANNER "time running backwards\n");
@@ -210,7 +204,8 @@ static int get_sample(void)
}
last_t2 = t2;
- total = time_to_us(time_sub(t2, start)); /* sample width */
+ /* sample width */
+ total = div_u64(t2 - start, NSEC_PER_USEC);
/* Check for possible overflows */
if (total < last_total) {
@@ -220,7 +215,7 @@ static int get_sample(void)
last_total = total;
/* This checks the inner loop (t1 to t2) */
- diff = time_to_us(time_sub(t2, t1)); /* current diff */
+ diff = div_u64(t2 - t1, NSEC_PER_USEC);
if (diff > thresh || outer_diff > thresh) {
if (!count)
@@ -251,15 +246,11 @@ static int get_sample(void)
ret = 1;
- /* We read in microseconds */
- if (nmi_total_ts)
- do_div(nmi_total_ts, NSEC_PER_USEC);
-
hwlat_data.count++;
s.seqnum = hwlat_data.count;
s.duration = sample;
s.outer_duration = outer_sample;
- s.nmi_total_ts = nmi_total_ts;
+ s.nmi_total_ts = div_u64(nmi_total_ts, NSEC_PER_USEC);
s.nmi_count = nmi_count;
s.count = count;
trace_hwlat_sample(&s);
next prev parent reply other threads:[~2020-05-16 0:12 UTC|newest]
Thread overview: 159+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-15 23:45 [patch V6 00/37] x86/entry: Rework leftovers and merge plan Thomas Gleixner
2020-05-15 23:45 ` Thomas Gleixner [this message]
2020-05-19 21:26 ` [patch V6 01/37] tracing/hwlat: Use ktime_get_mono_fast_ns() Steven Rostedt
2020-05-19 21:45 ` Thomas Gleixner
2020-05-19 22:18 ` Steven Rostedt
2020-05-20 19:51 ` Thomas Gleixner
2020-05-20 20:14 ` Peter Zijlstra
2020-05-20 22:20 ` Thomas Gleixner
2020-05-15 23:45 ` [patch V6 02/37] tracing/hwlat: Split ftrace_nmi_enter/exit() Thomas Gleixner
2020-05-19 22:23 ` Steven Rostedt
2020-05-15 23:45 ` [patch V6 03/37] nmi, tracing: Provide nmi_enter/exit_notrace() Thomas Gleixner
2020-05-17 5:12 ` Andy Lutomirski
2020-05-19 22:24 ` Steven Rostedt
2020-05-15 23:45 ` [patch V6 04/37] x86: Make hardware latency tracing explicit Thomas Gleixner
2020-05-17 5:36 ` Andy Lutomirski
2020-05-17 8:48 ` Thomas Gleixner
2020-05-18 5:50 ` Andy Lutomirski
2020-05-18 8:03 ` Thomas Gleixner
2020-05-18 20:42 ` Andy Lutomirski
2020-05-18 8:01 ` Peter Zijlstra
2020-05-18 8:05 ` Thomas Gleixner
2020-05-18 8:08 ` Peter Zijlstra
2020-05-20 20:09 ` Thomas Gleixner
2020-05-20 20:14 ` Andy Lutomirski
2020-05-20 22:20 ` Thomas Gleixner
2020-05-15 23:45 ` [patch V6 05/37] genirq: Provide irq_enter/exit_rcu() Thomas Gleixner
2020-05-18 23:06 ` Andy Lutomirski
2020-05-15 23:45 ` [patch V6 06/37] genirq: Provde __irq_enter/exit_raw() Thomas Gleixner
2020-05-18 23:07 ` Andy Lutomirski
2020-05-15 23:45 ` [patch V6 07/37] x86/entry: Provide helpers for execute on irqstack Thomas Gleixner
2020-05-18 23:11 ` Andy Lutomirski
2020-05-18 23:46 ` Andy Lutomirski
2020-05-18 23:53 ` Thomas Gleixner
2020-05-18 23:56 ` Andy Lutomirski
2020-05-20 12:35 ` Thomas Gleixner
2020-05-20 15:09 ` Andy Lutomirski
2020-05-20 15:27 ` Thomas Gleixner
2020-05-20 15:36 ` Andy Lutomirski
2020-05-18 23:51 ` Thomas Gleixner
2020-05-15 23:45 ` [patch V6 08/37] x86/entry/64: Move do_softirq_own_stack() to C Thomas Gleixner
2020-05-18 23:48 ` Andy Lutomirski
2020-05-15 23:45 ` [patch V6 09/37] x86/entry: Split idtentry_enter/exit() Thomas Gleixner
2020-05-18 23:49 ` Andy Lutomirski
2020-05-19 8:25 ` Thomas Gleixner
2020-05-15 23:45 ` [patch V6 10/37] x86/entry: Switch XEN/PV hypercall entry to IDTENTRY Thomas Gleixner
2020-05-19 17:06 ` Andy Lutomirski
2020-05-19 18:57 ` Thomas Gleixner
2020-05-19 19:44 ` Andy Lutomirski
2020-05-20 8:06 ` Jürgen Groß
2020-05-20 11:31 ` Andrew Cooper
2020-05-20 14:13 ` Thomas Gleixner
2020-05-20 15:16 ` Andy Lutomirski
2020-05-20 17:22 ` Andy Lutomirski
2020-05-20 19:16 ` Thomas Gleixner
2020-05-20 23:21 ` Andy Lutomirski
2020-05-21 10:45 ` Thomas Gleixner
2020-05-21 2:23 ` Boris Ostrovsky
2020-05-21 7:08 ` Thomas Gleixner
2020-05-15 23:45 ` [patch V6 11/37] x86/entry/64: Simplify idtentry_body Thomas Gleixner
2020-05-19 17:06 ` Andy Lutomirski
2020-05-15 23:45 ` [patch V6 12/37] x86/entry: Provide idtentry_entry/exit_cond_rcu() Thomas Gleixner
2020-05-19 17:08 ` Andy Lutomirski
2020-05-19 19:00 ` Thomas Gleixner
2020-05-19 20:20 ` Thomas Gleixner
2020-05-19 20:24 ` Andy Lutomirski
2020-05-19 21:20 ` Thomas Gleixner
2020-05-20 0:26 ` Andy Lutomirski
2020-05-20 2:23 ` Paul E. McKenney
2020-05-20 15:36 ` Andy Lutomirski
2020-05-20 16:51 ` Andy Lutomirski
2020-05-20 18:05 ` Paul E. McKenney
2020-05-20 19:49 ` Thomas Gleixner
2020-05-20 22:15 ` Paul E. McKenney
2020-05-20 23:25 ` Paul E. McKenney
2020-05-21 8:31 ` Thomas Gleixner
2020-05-21 13:39 ` Paul E. McKenney
2020-05-21 18:41 ` Thomas Gleixner
2020-05-21 19:04 ` Paul E. McKenney
2020-05-20 18:32 ` Thomas Gleixner
2020-05-20 19:24 ` Thomas Gleixner
2020-05-20 19:42 ` Paul E. McKenney
2020-05-20 17:38 ` Paul E. McKenney
2020-05-20 17:47 ` Andy Lutomirski
2020-05-20 18:11 ` Paul E. McKenney
2020-05-20 14:19 ` Thomas Gleixner
2020-05-27 8:12 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-15 23:46 ` [patch V6 13/37] x86/entry: Switch page fault exception to IDTENTRY_RAW Thomas Gleixner
2020-05-19 20:12 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 14/37] x86/entry: Remove the transition leftovers Thomas Gleixner
2020-05-19 20:13 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 15/37] x86/entry: Change exit path of xen_failsafe_callback Thomas Gleixner
2020-05-19 20:14 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 16/37] x86/entry/64: Remove error_exit Thomas Gleixner
2020-05-19 20:14 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 17/37] x86/entry/32: Remove common_exception Thomas Gleixner
2020-05-19 20:14 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 18/37] x86/irq: Use generic irq_regs implementation Thomas Gleixner
2020-05-15 23:46 ` [patch V6 19/37] x86/irq: Convey vector as argument and not in ptregs Thomas Gleixner
2020-05-19 20:19 ` Andy Lutomirski
2020-05-21 13:22 ` Thomas Gleixner
2020-05-22 18:48 ` Boris Ostrovsky
2020-05-22 19:26 ` Josh Poimboeuf
2020-05-22 19:54 ` Thomas Gleixner
2020-05-15 23:46 ` [patch V6 20/37] x86/irq/64: Provide handle_irq() Thomas Gleixner
2020-05-19 20:21 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 21/37] x86/entry: Add IRQENTRY_IRQ macro Thomas Gleixner
2020-05-19 20:27 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 22/37] x86/entry: Use idtentry for interrupts Thomas Gleixner
2020-05-19 20:28 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 23/37] x86/entry: Provide IDTENTRY_SYSVEC Thomas Gleixner
2020-05-20 0:29 ` Andy Lutomirski
2020-05-20 15:07 ` Thomas Gleixner
2020-05-15 23:46 ` [patch V6 24/37] x86/entry: Convert APIC interrupts to IDTENTRY_SYSVEC Thomas Gleixner
2020-05-20 0:27 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 25/37] x86/entry: Convert SMP system vectors " Thomas Gleixner
2020-05-20 0:28 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 26/37] x86/entry: Convert various system vectors Thomas Gleixner
2020-05-20 0:30 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 27/37] x86/entry: Convert KVM vectors to IDTENTRY_SYSVEC Thomas Gleixner
2020-05-20 0:30 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 28/37] x86/entry: Convert various hypervisor " Thomas Gleixner
2020-05-20 0:31 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 29/37] x86/entry: Convert XEN hypercall vector " Thomas Gleixner
2020-05-20 0:31 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 30/37] x86/entry: Convert reschedule interrupt to IDTENTRY_RAW Thomas Gleixner
2020-05-19 23:57 ` Andy Lutomirski
2020-05-20 15:08 ` Thomas Gleixner
2020-05-15 23:46 ` [patch V6 31/37] x86/entry: Remove the apic/BUILD interrupt leftovers Thomas Gleixner
2020-05-20 0:32 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 32/37] x86/entry/64: Remove IRQ stack switching ASM Thomas Gleixner
2020-05-20 0:33 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 33/37] x86/entry: Make enter_from_user_mode() static Thomas Gleixner
2020-05-20 0:34 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 34/37] x86/entry/32: Remove redundant irq disable code Thomas Gleixner
2020-05-20 0:35 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 35/37] x86/entry/64: Remove TRACE_IRQS_*_DEBUG Thomas Gleixner
2020-05-20 0:46 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 36/37] x86/entry: Move paranoid irq tracing out of ASM code Thomas Gleixner
2020-05-20 0:53 ` Andy Lutomirski
2020-05-20 15:16 ` Thomas Gleixner
2020-05-20 17:13 ` Andy Lutomirski
2020-05-20 18:33 ` Thomas Gleixner
2020-05-15 23:46 ` [patch V6 37/37] x86/entry: Remove the TRACE_IRQS cruft Thomas Gleixner
2020-05-18 23:07 ` Andy Lutomirski
2020-05-16 17:18 ` [patch V6 00/37] x86/entry: Rework leftovers and merge plan Paul E. McKenney
2020-05-19 12:28 ` Joel Fernandes
2020-05-18 16:07 ` Peter Zijlstra
2020-05-18 18:53 ` Thomas Gleixner
2020-05-19 8:29 ` Peter Zijlstra
2020-05-18 20:24 ` Thomas Gleixner
2020-05-19 8:38 ` Peter Zijlstra
2020-05-19 9:02 ` Peter Zijlstra
2020-05-23 2:52 ` Lai Jiangshan
2020-05-23 13:08 ` Peter Zijlstra
2020-06-15 16:17 ` Peter Zijlstra
2020-05-19 9:06 ` Thomas Gleixner
2020-05-19 18:37 ` Steven Rostedt
2020-05-19 19:09 ` Thomas Gleixner
2020-05-19 19:13 ` Steven Rostedt
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