Re: Reading EeePC900 battery info causes stalls

[Alexey Starikovskiy <aystarik@gmail.com>]

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Sitsofe Wheeler wrote:
> Hi Alexey,
>
> Alexey Starikovskiy wrote:
>> I think the least troubling place to add cond_resched() is then 
>> ACPICA is exiting interpreter.
>> Please check if the attached patch helps with latencies.
>
> There was no real change (latency was still bad). If you look at the 
> trace (before your patch) on 
> http://sucs.org/~sits/test/eeepc-debug/20080923/latency_trace.gz 
> (700kbyte compressed, 15Mbytes uncompressed) you can see that 
> acpi_ex_exit_interpreter is only called once near the end of the trace:
>
>      cat-5901    0.N.. 270496us : acpi_ex_exit_interpreter 
> (acpi_ev_address_space_dispatch)
>
> By then the time had already been racked up...
>
Ok, let's add it to the end of acpi_ps_complete_op() then... They appear 
every 100usec or so...


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diff --git a/drivers/acpi/parser/psloop.c b/drivers/acpi/parser/psloop.c
index c06238e..33cd061 100644
--- a/drivers/acpi/parser/psloop.c
+++ b/drivers/acpi/parser/psloop.c
@@ -564,6 +564,8 @@ acpi_ps_get_arguments(struct acpi_walk_state *walk_state,
  *
  ******************************************************************************/
 
+#include <linux/sched.h>
+
 static acpi_status
 acpi_ps_complete_op(struct acpi_walk_state *walk_state,
 		    union acpi_parse_object **op, acpi_status status)
@@ -719,6 +721,8 @@ acpi_ps_complete_op(struct acpi_walk_state *walk_state,
 		*op = NULL;
 	}
 
+	cond_resched();
+
 	return_ACPI_STATUS(AE_OK);
 }