From: John Stultz <john.stultz@linaro.org>
To: lkml <linux-kernel@vger.kernel.org>
Cc: John Stultz <john.stultz@linaro.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Prarit Bhargava <prarit@redhat.com>,
Richard Cochran <richardcochran@gmail.com>
Subject: [PATCH 21/21] time: Rework debugging variables so they aren't global
Date: Wed, 1 Apr 2015 20:34:41 -0700 [thread overview]
Message-ID: <1427945681-29972-22-git-send-email-john.stultz@linaro.org> (raw)
In-Reply-To: <1427945681-29972-1-git-send-email-john.stultz@linaro.org>
Ingo suggested that the timekeeping debugging variables
recently added should not be global, and should be tied
to the timekeeper's read_base.
Thus this patch implements that suggestion.
I'm a little hesitant here, since the tkr structure
has been carefully designed to fit in a cacheline.
However, these additions are all at the end of the
structure and are conditionally compiled.
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
include/linux/timekeeper_internal.h | 18 +++++++++++++++++-
kernel/time/timekeeping.c | 33 ++++++++++-----------------------
2 files changed, 27 insertions(+), 24 deletions(-)
diff --git a/include/linux/timekeeper_internal.h b/include/linux/timekeeper_internal.h
index fb86963..9b33027 100644
--- a/include/linux/timekeeper_internal.h
+++ b/include/linux/timekeeper_internal.h
@@ -20,9 +20,13 @@
* @shift: Shift value for scaled math conversion
* @xtime_nsec: Shifted (fractional) nano seconds offset for readout
* @base: ktime_t (nanoseconds) base time for readout
+ * @last_warning: Warning ratelimiter (DEBUG_TIMEKEEPING)
+ * @underflow_seen: Underflow warning flag (DEBUG_TIMEKEEPING)
+ * @overflow_seen: Overflow warning flag (DEBUG_TIMEKEEPING)
*
* This struct has size 56 byte on 64 bit. Together with a seqcount it
- * occupies a single 64byte cache line.
+ * occupies a single 64byte cache line (when DEBUG_TIMEKEEPING is not
+ * enabled).
*
* The struct is separate from struct timekeeper as it is also used
* for a fast NMI safe accessors.
@@ -36,6 +40,18 @@ struct tk_read_base {
u32 shift;
u64 xtime_nsec;
ktime_t base;
+#ifdef CONFIG_DEBUG_TIMEKEEPING
+ long last_warning;
+ /*
+ * These simple flag variables are managed
+ * without locks, which is racy, but ok since
+ * we don't really care about being super
+ * precise about how many events were seen,
+ * just that a problem was observed.
+ */
+ int underflow_seen;
+ int overflow_seen;
+#endif
};
/**
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 676896e..ad7a80f 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -118,19 +118,6 @@ static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
#ifdef CONFIG_DEBUG_TIMEKEEPING
#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
-/*
- * These simple flag variables are managed
- * without locks, which is racy, but ok since
- * we don't really care about being super
- * precise about how many events were seen,
- * just that a problem was observed.
- */
-static int timekeeping_underflow_seen;
-static int timekeeping_overflow_seen;
-
-/* last_warning is only modified under the timekeeping lock */
-static long timekeeping_last_warning;
-
static void timekeeping_check_update(struct tk_read_base *tkr, cycle_t offset)
{
@@ -149,24 +136,24 @@ static void timekeeping_check_update(struct tk_read_base *tkr, cycle_t offset)
}
}
- if (timekeeping_underflow_seen) {
- if (jiffies - timekeeping_last_warning > WARNING_FREQ) {
+ if (tkr->underflow_seen) {
+ if (jiffies - tkr->last_warning > WARNING_FREQ) {
printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
printk_deferred(" Your kernel is probably still fine.\n");
- timekeeping_last_warning = jiffies;
+ tkr->last_warning = jiffies;
}
- timekeeping_underflow_seen = 0;
+ tkr->underflow_seen = 0;
}
- if (timekeeping_overflow_seen) {
- if (jiffies - timekeeping_last_warning > WARNING_FREQ) {
+ if (tkr->overflow_seen) {
+ if (jiffies - tkr->last_warning > WARNING_FREQ) {
printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
printk_deferred(" Your kernel is probably still fine.\n");
- timekeeping_last_warning = jiffies;
+ tkr->last_warning = jiffies;
}
- timekeeping_overflow_seen = 0;
+ tkr->overflow_seen = 0;
}
}
@@ -197,13 +184,13 @@ static inline cycle_t timekeeping_get_delta(struct tk_read_base *tkr)
* mask-relative negative values.
*/
if (unlikely((~delta & mask) < (mask >> 3))) {
- timekeeping_underflow_seen = 1;
+ tkr->underflow_seen = 1;
delta = 0;
}
/* Cap delta value to the max_cycles values to avoid mult overflows */
if (unlikely(delta > max)) {
- timekeeping_overflow_seen = 1;
+ tkr->overflow_seen = 1;
delta = tkr->clock->max_cycles;
}
--
1.9.1
next prev parent reply other threads:[~2015-04-02 3:36 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-02 3:34 [PATCH 00/21] 4.1 time and rtc changes for tip/timers/core John Stultz
2015-04-02 3:34 ` [PATCH 01/21] time: Add y2038 safe read_boot_clock64() John Stultz
2015-04-03 8:15 ` [tip:timers/core] " tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 02/21] time: Add y2038 safe read_persistent_clock64() John Stultz
2015-04-03 8:15 ` [tip:timers/core] " tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 03/21] time: Add y2038 safe update_persistent_clock64() John Stultz
2015-04-03 8:16 ` [tip:timers/core] time: Add y2038 safe update_persistent_clock64( ) tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 04/21] ARM: OMAP: 32k counter: Provide y2038-safe omap_read_persistent_clock() replacement John Stultz
2015-04-03 8:16 ` [tip:timers/core] " tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 05/21] ARM: tegra: clock: Provide y2038-safe tegra_read_persistent_clock() replacement John Stultz
2015-04-03 8:16 ` [tip:timers/core] clocksource/drivers/tegra: " tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 06/21] ARM: time: Provide read_boot_clock64() and read_persistent_clock64() John Stultz
2015-04-03 8:17 ` [tip:timers/core] ARM, clocksource/drivers: Provide read_boot_clock64() and read_persistent_clock64() and use them tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 07/21] rtc: Provide y2038 safe rtc_class_ops.set_mmss() replacement John Stultz
2015-04-03 8:17 ` [tip:timers/core] drivers/rtc: " tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 08/21] rtc/test: Update driver to address y2038/y2106 issues John Stultz
2015-04-03 8:17 ` [tip:timers/core] drivers/rtc/test: " tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 09/21] rtc/ab3100: " John Stultz
2015-04-03 8:17 ` [tip:timers/core] drivers/rtc/ab3100: " tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 10/21] rtc/mc13xxx: " John Stultz
2015-04-03 8:18 ` [tip:timers/core] drivers/rtc/mc13xxx: " tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 11/21] rtc/mxc: Modify rtc_update_alarm() not to touch the alarm time John Stultz
2015-04-03 8:18 ` [tip:timers/core] drivers/rtc/mxc: " tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 12/21] rtc/mxc: Convert get_alarm_or_time()/set_alarm_or_time() to use time64_t John Stultz
2015-04-03 8:18 ` [tip:timers/core] drivers/rtc/mxc: Convert get_alarm_or_time()/ set_alarm_or_time() " tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 13/21] rtc/mxc: Update driver to address y2038/y2106 issues John Stultz
2015-04-03 8:19 ` [tip:timers/core] drivers/rtc/mxc: Update driver to address y2038 /y2106 issues tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 14/21] alpha: rtc: Change to use rtc_class_ops's set_mmss64() John Stultz
2015-04-03 8:19 ` [tip:timers/core] alpha, rtc: Change to use rtc_class_ops' s set_mmss64() tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 15/21] time: Don't build timekeeping_inject_sleeptime64() if no one uses it John Stultz
2015-04-03 8:19 ` [tip:timers/core] time: Don' t " tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 16/21] rtc: Remove redundant rtc_valid_tm() from rtc_resume() John Stultz
2015-04-03 8:19 ` [tip:timers/core] drivers/rtc: " tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 17/21] time: Fix a bug in timekeeping_suspend() with no persistent clock John Stultz
2015-04-03 6:16 ` Ingo Molnar
2015-04-03 8:20 ` [tip:timers/core] " tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 18/21] time: rtc: Don't bother into rtc_resume() for the nonstop clocksource John Stultz
2015-04-03 8:20 ` [tip:timers/core] time, drivers/rtc: Don't bother with rtc_resume () " tip-bot for Xunlei Pang
2015-04-02 3:34 ` [PATCH 19/21] clocksource: Improve comment explaining clocks_calc_max_nsecs()'s 50% safety margin John Stultz
2015-04-02 8:50 ` Peter Zijlstra
2015-04-02 17:30 ` John Stultz
2015-04-02 18:34 ` Peter Zijlstra
2015-04-02 18:41 ` John Stultz
2015-04-02 18:43 ` Peter Zijlstra
2015-04-02 18:50 ` John Stultz
2015-04-02 19:04 ` Peter Zijlstra
2015-04-03 8:20 ` [tip:timers/core] " tip-bot for John Stultz
2015-04-02 3:34 ` [PATCH 20/21] timekeeping: Change timekeeping_check_update() to take a tk_read_base John Stultz
2015-04-02 3:34 ` John Stultz [this message]
2015-04-02 7:47 ` [PATCH 21/21] time: Rework debugging variables so they aren't global Peter Zijlstra
2015-04-02 7:51 ` Ingo Molnar
2015-04-02 8:36 ` Peter Zijlstra
2015-04-02 8:41 ` Peter Zijlstra
2015-04-02 17:32 ` John Stultz
2015-04-03 6:21 ` Ingo Molnar
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1427945681-29972-22-git-send-email-john.stultz@linaro.org \
--to=john.stultz@linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=prarit@redhat.com \
--cc=richardcochran@gmail.com \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).