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Message-Id: <cb7202971ae70e5438f112e28f9a13e3c3aea4e6.1451558672.git.tst@schoebel-theuer.de>
Date: Thu, 31 Dec 2015 12:36:06 +0100
From: Thomas Schoebel-Theuer <tst@...oebel-theuer.de>
To: linux-kernel@...r.kernel.org, tst@...oebel-theuer.de
Subject: [RFC 11/31] mars: add new module lib_timing
Signed-off-by: Thomas Schoebel-Theuer <tst@...oebel-theuer.de>
---
drivers/staging/mars/lib/lib_timing.c | 71 +++++++++++++
include/linux/brick/lib_timing.h | 181 ++++++++++++++++++++++++++++++++++
2 files changed, 252 insertions(+)
create mode 100644 drivers/staging/mars/lib/lib_timing.c
create mode 100644 include/linux/brick/lib_timing.h
diff --git a/drivers/staging/mars/lib/lib_timing.c b/drivers/staging/mars/lib/lib_timing.c
new file mode 100644
index 0000000..7421dc4
--- /dev/null
+++ b/drivers/staging/mars/lib/lib_timing.c
@@ -0,0 +1,71 @@
+/*
+ * MARS Long Distance Replication Software
+ *
+ * Copyright (C) 2010-2014 Thomas Schoebel-Theuer
+ * Copyright (C) 2011-2014 1&1 Internet AG
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/brick/lib_timing.h>
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#ifdef CONFIG_DEBUG_KERNEL
+
+int report_timing(struct timing_stats *tim, char *str, int maxlen)
+{
+ int len = 0;
+ int time = 1;
+ int resol = 1;
+
+ static const char * const units[] = {
+ "us",
+ "ms",
+ "s",
+ "ERROR"
+ };
+ const char *unit = units[0];
+ int unit_index = 0;
+ int i;
+
+ for (i = 0; i < TIMING_MAX; i++) {
+ int this_len = scnprintf(str,
+
+ maxlen,
+ "<%d%s = %d (%lld) ",
+ resol,
+ unit,
+ tim->tim_count[i],
+ (long long)tim->tim_count[i] * time);
+ str += this_len;
+ len += this_len;
+ maxlen -= this_len;
+ if (maxlen <= 1)
+ break;
+ resol <<= 1;
+ time <<= 1;
+ if (resol >= 1000) {
+ resol = 1;
+ unit = units[++unit_index];
+ }
+ }
+ return len;
+}
+
+#endif /* CONFIG_DEBUG_KERNEL */
+
+struct threshold global_io_threshold = {
+ .thr_limit = 30 * 1000000, /* 30 seconds */
+ .thr_factor = 100,
+ .thr_plus = 0,
+};
diff --git a/include/linux/brick/lib_timing.h b/include/linux/brick/lib_timing.h
new file mode 100644
index 0000000..8a7a1e9
--- /dev/null
+++ b/include/linux/brick/lib_timing.h
@@ -0,0 +1,181 @@
+/*
+ * MARS Long Distance Replication Software
+ *
+ * Copyright (C) 2010-2014 Thomas Schoebel-Theuer
+ * Copyright (C) 2011-2014 1&1 Internet AG
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef LIB_TIMING_H
+#define LIB_TIMING_H
+
+#include <linux/sched.h>
+
+/* Simple infrastructure for timing of arbitrary operations and creation
+ * of some simple histogram statistics.
+ */
+
+#define TIMING_MAX 24
+
+struct timing_stats {
+#ifdef CONFIG_DEBUG_KERNEL
+ int tim_count[TIMING_MAX];
+
+#endif
+};
+
+#define _TIME_THIS(_stamp1, _stamp2, _CODE) \
+ ({ \
+ (_stamp1) = cpu_clock(raw_smp_processor_id()); \
+ \
+ _CODE; \
+ \
+ (_stamp2) = cpu_clock(raw_smp_processor_id()); \
+ (_stamp2) - (_stamp1); \
+ })
+
+#define TIME_THIS(_CODE) \
+ ({ \
+ unsigned long long _stamp1; \
+ unsigned long long _stamp2; \
+ _TIME_THIS(_stamp1, _stamp2, _CODE); \
+ })
+
+#ifdef CONFIG_DEBUG_KERNEL
+
+#define _TIME_STATS(_timing, _stamp1, _stamp2, _CODE) \
+ ({ \
+ unsigned long long _time; \
+ unsigned long _tmp; \
+ int _i; \
+ \
+ _time = _TIME_THIS(_stamp1, _stamp2, _CODE); \
+ \
+ _tmp = _time / 1000; /* convert to us */ \
+ _i = 0; \
+ while (_tmp > 0 && _i < TIMING_MAX - 1) { \
+ _tmp >>= 1; \
+ _i++; \
+ } \
+ (_timing)->tim_count[_i]++; \
+ _time; \
+ })
+
+#define TIME_STATS(_timing, _CODE) \
+ ({ \
+ unsigned long long _stamp1; \
+ unsigned long long _stamp2; \
+ _TIME_STATS(_timing, _stamp1, _stamp2, _CODE); \
+ })
+
+extern int report_timing(struct timing_stats *tim, char *str, int maxlen);
+
+#else /* CONFIG_DEBUG_KERNEL */
+
+#define _TIME_STATS(_timing, _stamp1, _stamp2, _CODE) \
+ ((void)_timing, (_stamp1) = (_stamp2) = cpu_clock(raw_smp_processor_id()), _CODE, 0)
+
+#define TIME_STATS(_timing, _CODE) \
+ ((void)_timing, _CODE, 0)
+
+#define report_timing(tim, str, maxlen) ((void)tim, 0)
+
+#endif /* CONFIG_DEBUG_KERNEL */
+
+/* A banning represents some overloaded resource.
+ *
+ * Whenever overload is detected, you should call banning_hit()
+ * telling that the overload is assumed / estimated to continue
+ * for some duration in time.
+ *
+ * ATTENTION! These operations are deliberately raceful.
+ * They are meant to deliver _hints_ (e.g. for IO scheduling
+ * decisions etc), not hard facts!
+ *
+ * If you need locking, just surround these operations
+ * with locking by yourself.
+ */
+struct banning {
+ long long ban_last_hit;
+
+ /* statistical */
+ int ban_renew_count;
+ int ban_count;
+};
+
+extern inline
+bool banning_hit(struct banning *ban, long long duration)
+{
+ long long now = cpu_clock(raw_smp_processor_id());
+ bool hit = ban->ban_last_hit >= now;
+ long long new_hit = now + duration;
+
+ ban->ban_renew_count++;
+ if (!ban->ban_last_hit || ban->ban_last_hit < new_hit) {
+ ban->ban_last_hit = new_hit;
+ ban->ban_count++;
+ }
+ return hit;
+}
+
+extern inline
+bool banning_is_hit(struct banning *ban)
+{
+ long long now = cpu_clock(raw_smp_processor_id());
+
+ return (ban->ban_last_hit && ban->ban_last_hit >= now);
+}
+
+extern inline
+void banning_reset(struct banning *ban)
+{
+ ban->ban_last_hit = 0;
+}
+
+/* Threshold: trigger a banning whenever some latency threshold
+ * is exceeded.
+ */
+struct threshold {
+ struct banning *thr_ban;
+
+ struct threshold *thr_parent; /* support hierarchies */
+ /* tunables */
+ int thr_limit; /* in us */
+ int thr_factor; /* in % */
+ int thr_plus; /* in us */
+ /* statistical */
+ int thr_max; /* in ms */
+ int thr_triggered;
+ int thr_true_hit;
+};
+
+extern inline
+void threshold_check(struct threshold *thr, long long latency)
+{
+ int ms = latency >> 6; /* ignore small rounding error */
+ while (thr) {
+ if (ms > thr->thr_max)
+ thr->thr_max = ms;
+ if (thr->thr_limit &&
+ latency > (long long)thr->thr_limit * 1000) {
+ thr->thr_triggered++;
+ if (thr->thr_ban &&
+ !banning_hit(thr->thr_ban, latency * thr->thr_factor / 100 + thr->thr_plus * 1000))
+ thr->thr_true_hit++;
+ }
+ thr = thr->thr_parent;
+ }
+}
+
+extern struct threshold global_io_threshold;
+
+#endif
--
2.6.4
--
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