#define CPUSET_SUPER_MAGIC 0x27e0eb
+/* See "Frequency meter" comments, below. */
+
+struct fmeter {
+ int cnt; /* unprocessed events count */
+ int val; /* most recent output value */
+ time_t time; /* clock (secs) when val computed */
+ spinlock_t lock; /* guards read or write of above */
+};
+
struct cpuset {
unsigned long flags; /* "unsigned long" so bitops work */
cpumask_t cpus_allowed; /* CPUs allowed to tasks in cpuset */
* Copy of global cpuset_mems_generation as of the most
* recent time this cpuset changed its mems_allowed.
*/
- int mems_generation;
+ int mems_generation;
+
+ struct fmeter fmeter; /* memory_pressure filter */
};
/* bits in struct cpuset flags field */
};
static struct vfsmount *cpuset_mount;
-static struct super_block *cpuset_sb = NULL;
+static struct super_block *cpuset_sb;
/*
* We have two global cpuset semaphores below. They can nest.
return retval;
}
+/*
+ * Call with manage_sem held.
+ */
+
+static int update_memory_pressure_enabled(struct cpuset *cs, char *buf)
+{
+ if (simple_strtoul(buf, NULL, 10) != 0)
+ cpuset_memory_pressure_enabled = 1;
+ else
+ cpuset_memory_pressure_enabled = 0;
+ return 0;
+}
+
/*
* update_flag - read a 0 or a 1 in a file and update associated flag
* bit: the bit to update (CS_CPU_EXCLUSIVE, CS_MEM_EXCLUSIVE,
return 0;
}
+/*
+ * Frequency meter - How fast is some event occuring?
+ *
+ * These routines manage a digitally filtered, constant time based,
+ * event frequency meter. There are four routines:
+ * fmeter_init() - initialize a frequency meter.
+ * fmeter_markevent() - called each time the event happens.
+ * fmeter_getrate() - returns the recent rate of such events.
+ * fmeter_update() - internal routine used to update fmeter.
+ *
+ * A common data structure is passed to each of these routines,
+ * which is used to keep track of the state required to manage the
+ * frequency meter and its digital filter.
+ *
+ * The filter works on the number of events marked per unit time.
+ * The filter is single-pole low-pass recursive (IIR). The time unit
+ * is 1 second. Arithmetic is done using 32-bit integers scaled to
+ * simulate 3 decimal digits of precision (multiplied by 1000).
+ *
+ * With an FM_COEF of 933, and a time base of 1 second, the filter
+ * has a half-life of 10 seconds, meaning that if the events quit
+ * happening, then the rate returned from the fmeter_getrate()
+ * will be cut in half each 10 seconds, until it converges to zero.
+ *
+ * It is not worth doing a real infinitely recursive filter. If more
+ * than FM_MAXTICKS ticks have elapsed since the last filter event,
+ * just compute FM_MAXTICKS ticks worth, by which point the level
+ * will be stable.
+ *
+ * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
+ * arithmetic overflow in the fmeter_update() routine.
+ *
+ * Given the simple 32 bit integer arithmetic used, this meter works
+ * best for reporting rates between one per millisecond (msec) and
+ * one per 32 (approx) seconds. At constant rates faster than one
+ * per msec it maxes out at values just under 1,000,000. At constant
+ * rates between one per msec, and one per second it will stabilize
+ * to a value N*1000, where N is the rate of events per second.
+ * At constant rates between one per second and one per 32 seconds,
+ * it will be choppy, moving up on the seconds that have an event,
+ * and then decaying until the next event. At rates slower than
+ * about one in 32 seconds, it decays all the way back to zero between
+ * each event.
+ */
+
+#define FM_COEF 933 /* coefficient for half-life of 10 secs */
+#define FM_MAXTICKS ((time_t)99) /* useless computing more ticks than this */
+#define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */
+#define FM_SCALE 1000 /* faux fixed point scale */
+
+/* Initialize a frequency meter */
+static void fmeter_init(struct fmeter *fmp)
+{
+ fmp->cnt = 0;
+ fmp->val = 0;
+ fmp->time = 0;
+ spin_lock_init(&fmp->lock);
+}
+
+/* Internal meter update - process cnt events and update value */
+static void fmeter_update(struct fmeter *fmp)
+{
+ time_t now = get_seconds();
+ time_t ticks = now - fmp->time;
+
+ if (ticks == 0)
+ return;
+
+ ticks = min(FM_MAXTICKS, ticks);
+ while (ticks-- > 0)
+ fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
+ fmp->time = now;
+
+ fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
+ fmp->cnt = 0;
+}
+
+/* Process any previous ticks, then bump cnt by one (times scale). */
+static void fmeter_markevent(struct fmeter *fmp)
+{
+ spin_lock(&fmp->lock);
+ fmeter_update(fmp);
+ fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
+ spin_unlock(&fmp->lock);
+}
+
+/* Process any previous ticks, then return current value. */
+static int fmeter_getrate(struct fmeter *fmp)
+{
+ int val;
+
+ spin_lock(&fmp->lock);
+ fmeter_update(fmp);
+ val = fmp->val;
+ spin_unlock(&fmp->lock);
+ return val;
+}
+
/*
* Attack task specified by pid in 'pidbuf' to cpuset 'cs', possibly
* writing the path of the old cpuset in 'ppathbuf' if it needs to be
FILE_CPU_EXCLUSIVE,
FILE_MEM_EXCLUSIVE,
FILE_NOTIFY_ON_RELEASE,
+ FILE_MEMORY_PRESSURE_ENABLED,
+ FILE_MEMORY_PRESSURE,
FILE_TASKLIST,
} cpuset_filetype_t;
case FILE_MEMORY_MIGRATE:
retval = update_flag(CS_MEMORY_MIGRATE, cs, buffer);
break;
+ case FILE_MEMORY_PRESSURE_ENABLED:
+ retval = update_memory_pressure_enabled(cs, buffer);
+ break;
+ case FILE_MEMORY_PRESSURE:
+ retval = -EACCES;
+ break;
case FILE_TASKLIST:
retval = attach_task(cs, buffer, &pathbuf);
break;
case FILE_MEMORY_MIGRATE:
*s++ = is_memory_migrate(cs) ? '1' : '0';
break;
+ case FILE_MEMORY_PRESSURE_ENABLED:
+ *s++ = cpuset_memory_pressure_enabled ? '1' : '0';
+ break;
+ case FILE_MEMORY_PRESSURE:
+ s += sprintf(s, "%d", fmeter_getrate(&cs->fmeter));
+ break;
default:
retval = -EINVAL;
goto out;
.private = FILE_MEMORY_MIGRATE,
};
+static struct cftype cft_memory_pressure_enabled = {
+ .name = "memory_pressure_enabled",
+ .private = FILE_MEMORY_PRESSURE_ENABLED,
+};
+
+static struct cftype cft_memory_pressure = {
+ .name = "memory_pressure",
+ .private = FILE_MEMORY_PRESSURE,
+};
+
static int cpuset_populate_dir(struct dentry *cs_dentry)
{
int err;
return err;
if ((err = cpuset_add_file(cs_dentry, &cft_memory_migrate)) < 0)
return err;
+ if ((err = cpuset_add_file(cs_dentry, &cft_memory_pressure)) < 0)
+ return err;
if ((err = cpuset_add_file(cs_dentry, &cft_tasks)) < 0)
return err;
return 0;
INIT_LIST_HEAD(&cs->children);
atomic_inc(&cpuset_mems_generation);
cs->mems_generation = atomic_read(&cpuset_mems_generation);
+ fmeter_init(&cs->fmeter);
cs->parent = parent;
top_cpuset.cpus_allowed = CPU_MASK_ALL;
top_cpuset.mems_allowed = NODE_MASK_ALL;
+ fmeter_init(&top_cpuset.fmeter);
atomic_inc(&cpuset_mems_generation);
top_cpuset.mems_generation = atomic_read(&cpuset_mems_generation);
top_cpuset.dentry = root;
root->d_inode->i_op = &cpuset_dir_inode_operations;
err = cpuset_populate_dir(root);
+ /* memory_pressure_enabled is in root cpuset only */
+ if (err == 0)
+ err = cpuset_add_file(root, &cft_memory_pressure_enabled);
out:
return err;
}
return overlap;
}
+/*
+ * Collection of memory_pressure is suppressed unless
+ * this flag is enabled by writing "1" to the special
+ * cpuset file 'memory_pressure_enabled' in the root cpuset.
+ */
+
+int cpuset_memory_pressure_enabled;
+
+/**
+ * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
+ *
+ * Keep a running average of the rate of synchronous (direct)
+ * page reclaim efforts initiated by tasks in each cpuset.
+ *
+ * This represents the rate at which some task in the cpuset
+ * ran low on memory on all nodes it was allowed to use, and
+ * had to enter the kernels page reclaim code in an effort to
+ * create more free memory by tossing clean pages or swapping
+ * or writing dirty pages.
+ *
+ * Display to user space in the per-cpuset read-only file
+ * "memory_pressure". Value displayed is an integer
+ * representing the recent rate of entry into the synchronous
+ * (direct) page reclaim by any task attached to the cpuset.
+ **/
+
+void __cpuset_memory_pressure_bump(void)
+{
+ struct cpuset *cs;
+
+ task_lock(current);
+ cs = current->cpuset;
+ fmeter_markevent(&cs->fmeter);
+ task_unlock(current);
+}
+
/*
* proc_cpuset_show()
* - Print tasks cpuset path into seq_file.
projects / linux-2.6 / commitdiff