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>

diff --git a/kernel/sched.c b/kernel/sched.c
index 8f03817e7dd37594470edc097aa774cca15b3d57..b59a44e1ea442f966daa0dfa099a1e3f7c9631e7 100644 (file)
--- 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 (file)
index 0000000..1c7283c
--- /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)