Alexey Starikovskiy wrote:
Sitsofe Wheeler wrote:
Alexey Starikovskiy wrote:
acpi_ps_parse_aml() is called not so often (~10000usec), so maybe it
is a "sweet spot"
The latency is pretty bad with this patch (assuming you did not want
it applied on top of your previous patch)
Here's the tail end of a full trace:
http://sucs.org/~sits/test/eeepc-debug/20080925/1250/latency_trace_all_tail.gz
(3.3Mbytes but close 100Mbytes when decompressed)
latency: 2912285 us, #1000038/5344107, CPU#0 | (M:desktop VP:0,
KP:0, SP:0 HP:0
)
Here's a complete (but filtered) trace:
http://sucs.org/~sits/test/eeepc-debug/20080925/1250/latency_trace.gz
latency: 315814 us, #227600/227600, CPU#0 | (M:desktop VP:0, KP:0,
SP:0 HP:0)
Ok, let's stick with previous patch then.
It will be somewhat difficult to push though, because the code we
touched belongs to ACPICA (multi-platform code),
so should not contain explicit Linux-only operands.
If you agree that the place is right, I'll make proper patch with all
needed redirections to
make ACPICA happy.
Ok, here is the ACPICA-friendly patch, please check if it's still good.
Regards,
Alex.
ACPICA: add preemption point after each opcode parse
From: Alexey Starikovskiy <astarikovskiy@xxxxxxx>
Signed-off-by: Alexey Starikovskiy <astarikovskiy@xxxxxxx>
---
drivers/acpi/parser/psloop.c | 2 ++
include/acpi/acmacros.h | 5 +++++
include/acpi/platform/aclinux.h | 6 ++++++
3 files changed, 13 insertions(+), 0 deletions(-)
diff --git a/drivers/acpi/parser/psloop.c b/drivers/acpi/parser/psloop.c
index c06238e..4647039 100644
--- a/drivers/acpi/parser/psloop.c
+++ b/drivers/acpi/parser/psloop.c
@@ -719,6 +719,8 @@ acpi_ps_complete_op(struct acpi_walk_state *walk_state,
*op = NULL;
}
+ ACPI_PREEMPTION_POINT();
+
return_ACPI_STATUS(AE_OK);
}
diff --git a/include/acpi/acmacros.h b/include/acpi/acmacros.h
index 57ab9e9..b402685 100644
--- a/include/acpi/acmacros.h
+++ b/include/acpi/acmacros.h
@@ -703,4 +703,9 @@ struct acpi_integer_overlay {
#endif /* ACPI_DBG_TRACK_ALLOCATIONS */
+/* Preemption point */
+#ifndef ACPI_PREEMPTION_POINT
+#define ACPI_PREEMPTION_POINT() /* no preemption */
+#endif
+
#endif /* ACMACROS_H */
diff --git a/include/acpi/platform/aclinux.h b/include/acpi/platform/aclinux.h
index 9af4645..029c8c0 100644
--- a/include/acpi/platform/aclinux.h
+++ b/include/acpi/platform/aclinux.h
@@ -53,6 +53,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/ctype.h>
+#include <linux/sched.h>
#include <asm/system.h>
#include <asm/atomic.h>
#include <asm/div64.h>
@@ -137,4 +138,9 @@ static inline void *acpi_os_acquire_object(acpi_cache_t * cache)
#define ACPI_ALLOCATE_ZEROED(a) acpi_os_allocate_zeroed(a)
#define ACPI_FREE(a) kfree(a)
+/*
+ * We need to show where it is safe to preempt execution of ACPICA
+ */
+#define ACPI_PREEMPTION_POINT() cond_resched()
+
#endif /* __ACLINUX_H__ */
