1 files changed, 178 insertions, 0 deletions

diff --git a/kernel/delayacct.c b/kernel/delayacct.c
new file mode 100644
index 000000000000..57ca3730205d
--- /dev/null
+++ b/kernel/delayacct.c
@@ -0,0 +1,178 @@
+/* delayacct.c - per-task delay accounting
+ *
+ * Copyright (C) Shailabh Nagar, IBM Corp. 2006
+ *
+ * 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 would 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/sched.h>
+#include <linux/slab.h>
+#include <linux/time.h>
+#include <linux/sysctl.h>
+#include <linux/delayacct.h>
+
+int delayacct_on __read_mostly = 1;     /* Delay accounting turned on/off */
+kmem_cache_t *delayacct_cache;
+
+static int __init delayacct_setup_disable(char *str)
+{
+        delayacct_on = 0;
+        return 1;
+}
+__setup("nodelayacct", delayacct_setup_disable);
+
+void delayacct_init(void)
+{
+        delayacct_cache = kmem_cache_create("delayacct_cache",
+                                        sizeof(struct task_delay_info),
+                                        0,
+                                        SLAB_PANIC,
+                                        NULL, NULL);
+        delayacct_tsk_init(&init_task);
+}
+
+void __delayacct_tsk_init(struct task_struct *tsk)
+{
+        spin_lock_init(&tsk->delays_lock);
+        /* No need to acquire tsk->delays_lock for allocation here unless
+           __delayacct_tsk_init called after tsk is attached to tasklist
+        */
+        tsk->delays = kmem_cache_zalloc(delayacct_cache, SLAB_KERNEL);
+        if (tsk->delays)
+                spin_lock_init(&tsk->delays->lock);
+}
+
+void __delayacct_tsk_exit(struct task_struct *tsk)
+{
+        struct task_delay_info *delays = tsk->delays;
+        spin_lock(&tsk->delays_lock);
+        tsk->delays = NULL;
+        spin_unlock(&tsk->delays_lock);
+        kmem_cache_free(delayacct_cache, delays);
+}
+
+/*
+ * Start accounting for a delay statistic using
+ * its starting timestamp (@start)
+ */
+
+static inline void delayacct_start(struct timespec *start)
+{
+        do_posix_clock_monotonic_gettime(start);
+}
+
+/*
+ * Finish delay accounting for a statistic using
+ * its timestamps (@start, @end), accumalator (@total) and @count
+ */
+
+static void delayacct_end(struct timespec *start, struct timespec *end,
+                                u64 *total, u32 *count)
+{
+        struct timespec ts;
+        s64 ns;
+
+        do_posix_clock_monotonic_gettime(end);
+        ts = timespec_sub(*end, *start);
+        ns = timespec_to_ns(&ts);
+        if (ns < 0)
+                return;
+
+        spin_lock(&current->delays->lock);
+        *total += ns;
+        (*count)++;
+        spin_unlock(&current->delays->lock);
+}
+
+void __delayacct_blkio_start(void)
+{
+        delayacct_start(&current->delays->blkio_start);
+}
+
+void __delayacct_blkio_end(void)
+{
+        if (current->delays->flags & DELAYACCT_PF_SWAPIN)
+                /* Swapin block I/O */
+                delayacct_end(&current->delays->blkio_start,
+                        &current->delays->blkio_end,
+                        &current->delays->swapin_delay,
+                        &current->delays->swapin_count);
+        else    /* Other block I/O */
+                delayacct_end(&current->delays->blkio_start,
+                        &current->delays->blkio_end,
+                        &current->delays->blkio_delay,
+                        &current->delays->blkio_count);
+}
+
+int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
+{
+        s64 tmp;
+        struct timespec ts;
+        unsigned long t1,t2,t3;
+
+        spin_lock(&tsk->delays_lock);
+
+        /* Though tsk->delays accessed later, early exit avoids
+         * unnecessary returning of other data
+         */
+        if (!tsk->delays)
+                goto done;
+
+        tmp = (s64)d->cpu_run_real_total;
+        cputime_to_timespec(tsk->utime + tsk->stime, &ts);
+        tmp += timespec_to_ns(&ts);
+        d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
+
+        /*
+         * No locking available for sched_info (and too expensive to add one)
+         * Mitigate by taking snapshot of values
+         */
+        t1 = tsk->sched_info.pcnt;
+        t2 = tsk->sched_info.run_delay;
+        t3 = tsk->sched_info.cpu_time;
+
+        d->cpu_count += t1;
+
+        jiffies_to_timespec(t2, &ts);
+        tmp = (s64)d->cpu_delay_total + timespec_to_ns(&ts);
+        d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
+
+        tmp = (s64)d->cpu_run_virtual_total + (s64)jiffies_to_usecs(t3) * 1000;
+        d->cpu_run_virtual_total =
+                (tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
+
+        /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
+
+        spin_lock(&tsk->delays->lock);
+        tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
+        d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
+        tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
+        d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
+        d->blkio_count += tsk->delays->blkio_count;
+        d->swapin_count += tsk->delays->swapin_count;
+        spin_unlock(&tsk->delays->lock);
+
+done:
+        spin_unlock(&tsk->delays_lock);
+        return 0;
+}
+
+__u64 __delayacct_blkio_ticks(struct task_struct *tsk)
+{
+        __u64 ret;
+
+        spin_lock(&tsk->delays->lock);
+        ret = nsec_to_clock_t(tsk->delays->blkio_delay +
+                                tsk->delays->swapin_delay);
+        spin_unlock(&tsk->delays->lock);
+        return ret;
+}
+