Instead of Con Koliva's approach to fix dyntick and the busmaster logic in
the ACPI idle handler (see
http://ck.kolivas.org/patches/dyn-ticks/split-out/dyntick-busmaster_support.patch
) I propose this different patch as a replacement. Its
skipped_since_bm_check() is broken, as it returns the number of ticks we
hope to go to sleep for _now_, not how long we slept last time.
Some test result:
ck:
*C2: type[C2] promotion[C3] demotion[C1] latency[001]
usage[00066141] time[00000000001817309417]
C3: type[C3] promotion[--] demotion[C2] latency[085]
usage[00005760] time[00000000000138436523]
At average, sleeping for 7 ticks when in C2
At average, sleeping for 6 ticks when in C3
me:
C2: type[C2] promotion[C3] demotion[C1] latency[001]
usage[00143551] time[00000000002930357624]
*C3: type[C3] promotion[--] demotion[C2] latency[085]
usage[00079181] time[00000000002733459218]
At average, sleeping for 5 ticks when in C2
At average, sleeping for 9 ticks when in C3
Not perfect yet (but see the next patch), but better.
Only avoid entering C3-type sleep if there is bus master activity at the
moment.
Also, bus mastering activity going on while we slept can be ignored.
Therefore, adjust the bm_check_timestamp accordingly.
Signed-off-by: Dominik Brodowski <[email protected]>
Index: working-tree/drivers/acpi/processor_idle.c
===================================================================
--- working-tree.orig/drivers/acpi/processor_idle.c
+++ working-tree/drivers/acpi/processor_idle.c
@@ -256,7 +256,7 @@ static void acpi_processor_idle(void)
pr->power.bm_check_timestamp = jiffies;
/*
- * Apply bus mastering demotion policy. Automatically demote
+ * If bus mastering is active, automatically demote
* to avoid a faulty transition. Note that the processor
* won't enter a low-power state during this call (to this
* funciton) but should upon the next.
@@ -267,7 +267,7 @@ static void acpi_processor_idle(void)
* qualification. This may, however, introduce DMA
* issues (e.g. floppy DMA transfer overrun/underrun).
*/
- if (pr->power.bm_activity & cx->demotion.threshold.bm) {
+ if (bm_status && cx->demotion.threshold.bm) {
local_irq_enable();
next_state = cx->demotion.state;
goto end;
@@ -391,6 +391,10 @@ static void acpi_processor_idle(void)
cx->time += (PM_TIMER_FREQUENCY / (2 * HZ));
}
+ if (pr->flags.bm_check)
+ pr->power.bm_check_timestamp += sleep_ticks /
+ (PM_TIMER_FREQUENCY / HZ);
+
next_state = pr->power.state;
/*
-
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