sched: /debug/sched_features

provide a text based interface to the scheduler features; this saves the
'user' from setting bits using decimal arithmetic.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 150 insertions, 22 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 8f03817e7dd3..b59a44e1ea44 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -68,6 +68,8 @@
 #include <linux/hrtimer.h>
 #include <linux/tick.h>
 #include <linux/bootmem.h>
+#include <linux/debugfs.h>
+#include <linux/ctype.h>
 
 #include <asm/tlb.h>
 #include <asm/irq_regs.h>
@@ -732,32 +734,148 @@ static void update_rq_clock(struct rq *rq)
 /*
  * Debugging: various feature bits
  */
+
+#define SCHED_FEAT(name, enabled)       \
+        __SCHED_FEAT_##name ,
+
 enum {
-        SCHED_FEAT_NEW_FAIR_SLEEPERS    = 1,
-        SCHED_FEAT_WAKEUP_PREEMPT       = 2,
-        SCHED_FEAT_START_DEBIT          = 4,
-        SCHED_FEAT_AFFINE_WAKEUPS       = 8,
-        SCHED_FEAT_CACHE_HOT_BUDDY      = 16,
-        SCHED_FEAT_SYNC_WAKEUPS         = 32,
-        SCHED_FEAT_HRTICK               = 64,
-        SCHED_FEAT_DOUBLE_TICK          = 128,
-        SCHED_FEAT_NORMALIZED_SLEEPER   = 256,
-        SCHED_FEAT_DEADLINE             = 512,
+#include "sched_features.h"
 };
 
+#undef SCHED_FEAT
+
+#define SCHED_FEAT(name, enabled)       \
+        (1UL << __SCHED_FEAT_##name) * enabled |
+
 const_debug unsigned int sysctl_sched_features =
-                SCHED_FEAT_NEW_FAIR_SLEEPERS    * 1 |
-                SCHED_FEAT_WAKEUP_PREEMPT       * 1 |
-                SCHED_FEAT_START_DEBIT          * 1 |
-                SCHED_FEAT_AFFINE_WAKEUPS       * 1 |
-                SCHED_FEAT_CACHE_HOT_BUDDY      * 1 |
-                SCHED_FEAT_SYNC_WAKEUPS         * 1 |
-                SCHED_FEAT_HRTICK               * 1 |
-                SCHED_FEAT_DOUBLE_TICK          * 0 |
-                SCHED_FEAT_NORMALIZED_SLEEPER   * 1 |
-                SCHED_FEAT_DEADLINE             * 1;
-
-#define sched_feat(x) (sysctl_sched_features & SCHED_FEAT_##x)
+#include "sched_features.h"
+        0;
+
+#undef SCHED_FEAT
+
+#ifdef CONFIG_SCHED_DEBUG
+#define SCHED_FEAT(name, enabled)       \
+        #name ,
+
+__read_mostly char *sched_feat_names[] = {
+#include "sched_features.h"
+        NULL
+};
+
+#undef SCHED_FEAT
+
+int sched_feat_open(struct inode *inode, struct file *filp)
+{
+        filp->private_data = inode->i_private;
+        return 0;
+}
+
+static ssize_t
+sched_feat_read(struct file *filp, char __user *ubuf,
+                size_t cnt, loff_t *ppos)
+{
+        char *buf;
+        int r = 0;
+        int len = 0;
+        int i;
+
+        for (i = 0; sched_feat_names[i]; i++) {
+                len += strlen(sched_feat_names[i]);
+                len += 4;
+        }
+
+        buf = kmalloc(len + 2, GFP_KERNEL);
+        if (!buf)
+                return -ENOMEM;
+
+        for (i = 0; sched_feat_names[i]; i++) {
+                if (sysctl_sched_features & (1UL << i))
+                        r += sprintf(buf + r, "%s ", sched_feat_names[i]);
+                else
+                        r += sprintf(buf + r, "no_%s ", sched_feat_names[i]);
+        }
+
+        r += sprintf(buf + r, "\n");
+        WARN_ON(r >= len + 2);
+
+        r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+
+        kfree(buf);
+
+        return r;
+}
+
+static ssize_t
+sched_feat_write(struct file *filp, const char __user *ubuf,
+                size_t cnt, loff_t *ppos)
+{
+        char buf[64];
+        char *cmp = buf;
+        int neg = 0;
+        int i;
+
+        if (cnt > 63)
+                cnt = 63;
+
+        if (copy_from_user(&buf, ubuf, cnt))
+                return -EFAULT;
+
+        buf[cnt] = 0;
+
+        if (strncmp(buf, "no_", 3) == 0) {
+                neg = 1;
+                cmp += 3;
+        }
+
+        for (i = 0; sched_feat_names[i]; i++) {
+                int len = strlen(sched_feat_names[i]);
+
+                if (strncmp(cmp, sched_feat_names[i], len) == 0) {
+                        if (neg)
+                                sysctl_sched_features &= ~(1UL << i);
+                        else
+                                sysctl_sched_features |= (1UL << i);
+                        break;
+                }
+        }
+
+        if (!sched_feat_names[i])
+                return -EINVAL;
+
+        filp->f_pos += cnt;
+
+        return cnt;
+}
+
+static struct file_operations sched_feat_fops = {
+        .open   = sched_feat_open,
+        .read   = sched_feat_read,
+        .write  = sched_feat_write,
+};
+
+static __init int sched_init_debug(void)
+{
+        int i, j, len;
+
+        for (i = 0; sched_feat_names[i]; i++) {
+                len = strlen(sched_feat_names[i]);
+
+                for (j = 0; j < len; j++) {
+                        sched_feat_names[i][j] =
+                                tolower(sched_feat_names[i][j]);
+                }
+        }
+
+        debugfs_create_file("sched_features", 0644, NULL, NULL,
+                        &sched_feat_fops);
+
+        return 0;
+}
+late_initcall(sched_init_debug);
+
+#endif
+
+#define sched_feat(x) (sysctl_sched_features & (1UL << __SCHED_FEAT_##x))
 
 /*
  * Number of tasks to iterate in a single balance run.
diff --git a/kernel/sched_features.h b/kernel/sched_features.h
new file mode 100644
index 000000000000..1c7283cb9581
--- /dev/null
+++ b/kernel/sched_features.h
@@ -0,0 +1,10 @@
+SCHED_FEAT(NEW_FAIR_SLEEPERS, 1)
+SCHED_FEAT(WAKEUP_PREEMPT, 1)
+SCHED_FEAT(START_DEBIT, 1)
+SCHED_FEAT(AFFINE_WAKEUPS, 1)
+SCHED_FEAT(CACHE_HOT_BUDDY, 1)
+SCHED_FEAT(SYNC_WAKEUPS, 1)
+SCHED_FEAT(HRTICK, 1)
+SCHED_FEAT(DOUBLE_TICK, 0)
+SCHED_FEAT(NORMALIZED_SLEEPER, 1)
+SCHED_FEAT(DEADLINE, 1)