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authorLinus Torvalds <torvalds@linux-foundation.org>2011-05-23 12:53:48 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-05-23 12:53:48 -0700
commit15a3d11b0f2ebdfb3591e411e268aa81998d4723 (patch)
tree56e1d7715653871f015341c7edabd08045f5fc28 /include
parent1f3a8e093f470ef193b0ca6011d90180331c8b53 (diff)
parentc8b281161dfa4bb5d5be63fb036ce19347b88c63 (diff)
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: sched: Increase SCHED_LOAD_SCALE resolution sched: Introduce SCHED_POWER_SCALE to scale cpu_power calculations sched: Cleanup set_load_weight()
Diffstat (limited to 'include')
-rw-r--r--include/linux/sched.h34
1 files changed, 28 insertions, 6 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 340f5ee57334..aaf71e08222c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -786,17 +786,39 @@ enum cpu_idle_type {
};
/*
- * sched-domains (multiprocessor balancing) declarations:
+ * Increase resolution of nice-level calculations for 64-bit architectures.
+ * The extra resolution improves shares distribution and load balancing of
+ * low-weight task groups (eg. nice +19 on an autogroup), deeper taskgroup
+ * hierarchies, especially on larger systems. This is not a user-visible change
+ * and does not change the user-interface for setting shares/weights.
+ *
+ * We increase resolution only if we have enough bits to allow this increased
+ * resolution (i.e. BITS_PER_LONG > 32). The costs for increasing resolution
+ * when BITS_PER_LONG <= 32 are pretty high and the returns do not justify the
+ * increased costs.
*/
+#if BITS_PER_LONG > 32
+# define SCHED_LOAD_RESOLUTION 10
+# define scale_load(w) ((w) << SCHED_LOAD_RESOLUTION)
+# define scale_load_down(w) ((w) >> SCHED_LOAD_RESOLUTION)
+#else
+# define SCHED_LOAD_RESOLUTION 0
+# define scale_load(w) (w)
+# define scale_load_down(w) (w)
+#endif
-/*
- * Increase resolution of nice-level calculations:
- */
-#define SCHED_LOAD_SHIFT 10
+#define SCHED_LOAD_SHIFT (10 + SCHED_LOAD_RESOLUTION)
#define SCHED_LOAD_SCALE (1L << SCHED_LOAD_SHIFT)
-#define SCHED_LOAD_SCALE_FUZZ SCHED_LOAD_SCALE
+/*
+ * Increase resolution of cpu_power calculations
+ */
+#define SCHED_POWER_SHIFT 10
+#define SCHED_POWER_SCALE (1L << SCHED_POWER_SHIFT)
+/*
+ * sched-domains (multiprocessor balancing) declarations:
+ */
#ifdef CONFIG_SMP
#define SD_LOAD_BALANCE 0x0001 /* Do load balancing on this domain. */
#define SD_BALANCE_NEWIDLE 0x0002 /* Balance when about to become idle */