The patch titled
timer: run calc_load halfway through each round_jiffies second
has been removed from the -mm tree. Its filename was
timer-run-calc_load-halfway-through-each-round_jiffies.patch
This patch was dropped because it seems to need more thought
------------------------------------------------------
Subject: timer: run calc_load halfway through each round_jiffies second
From: Simon Arlott <simon@xxxxxxxxxxx>
Whenever jiffies is started at a multiple of 5*HZ or wraps, calc_load is
run exactly on the second which is when tasks using round_jiffies will be
scheduled to run. This has a bad effect on the load average, making it
tend towards 1.00 if a task happens to run every time the load is being
calculated.
This changes calc_load so that it updates load half a second after any
tasks scheduled using round_jiffies.
Without this change or an appropriate equivalent, my change to cxacru
causes the load to stay around 1.00 even when mostly idle since it now
runs every second using round_jiffies:
> [ 332.416288] cxacru_poll_status(..), jiffies=5000 [start]
> [ 332.417312] calc_load(1), count=-1, jiffies=5001 [start]
> [ 332.417322] calc_load(1), count=4999, jiffies=5001 [finish]
> [ 332.423382] cxacru_poll_status(..), jiffies=5007, next=993 [finish]
Signed-off-by: Simon Arlott <simon@xxxxxxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/timer.c | 8 +++++---
1 files changed, 5 insertions(+), 3 deletions(-)
diff -puN kernel/timer.c~timer-run-calc_load-halfway-through-each-round_jiffies kernel/timer.c
--- a/kernel/timer.c~timer-run-calc_load-halfway-through-each-round_jiffies
+++ a/kernel/timer.c
@@ -1226,17 +1226,19 @@ EXPORT_SYMBOL(avenrun);
static inline void calc_load(unsigned long ticks)
{
unsigned long active_tasks; /* fixed-point */
- static int count = LOAD_FREQ;
+ static int count = LOAD_FREQ + HZ/2;
count -= ticks;
- if (unlikely(count < 0)) {
+ if (unlikely(count <= 0)) {
active_tasks = count_active_tasks();
do {
CALC_LOAD(avenrun[0], EXP_1, active_tasks);
CALC_LOAD(avenrun[1], EXP_5, active_tasks);
CALC_LOAD(avenrun[2], EXP_15, active_tasks);
count += LOAD_FREQ;
- } while (count < 0);
+ } while (count <= 0);
+
+ count = round_jiffies_relative(count + HZ/2) - HZ/2;
}
}
_
Patches currently in -mm which might be from simon@xxxxxxxxxxx are
usbatm-create-sysfs-link-device-from-atm-class-device.patch
cxacru-export-detailed-device-info-through-sysfs-updated.patch
maintainers-add-myself-for-cxacru-in-drivers-usb-atm.patch
timer-run-calc_load-halfway-through-each-round_jiffies.patch
-
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