* [PATCH] Re: How to completely disable async fastboot?
2009-04-16 1:31 ` Arjan van de Ven
@ 2009-04-16 1:48 ` Jeff Garzik
2009-04-17 18:45 ` Stefan Richter
1 sibling, 0 replies; 4+ messages in thread
From: Jeff Garzik @ 2009-04-16 1:48 UTC (permalink / raw)
To: Arjan van de Ven; +Cc: LKML, Andrew Morton
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Arjan van de Ven wrote:
> On Wed, 15 Apr 2009 20:20:32 -0400
> Jeff Garzik <jeff@garzik.org> wrote:
>
>> The following commit
>>
>>> commit 9710794383ee5008d67f1a6613a4717bf6de47bc
>>> Author: Arjan van de Ven <arjan@linux.intel.com>
>>> Date: Sun Mar 15 11:11:44 2009 -0700
>>>
>>> async: remove the temporary (2.6.29) "async is off by default"
>>> code
>> not only changes a default, it completely removes the ability to turn
>> off async AFAICS.
>
> this is on the request of Andrew and others who want to be able to use
> these API's (soon) in an "forced offload" scenario.
>
>> At present, I need to turn this off to debug boot-time operation.
>
> can you give some details? Maybe I can help suggest things...
Too much shit is occurring in parallel, which completely obscures the
operation of the driver I am currently debugging. A new and unwelcome
behavior, as it is directly impacting workflow.
Commit 9710794383ee5008d67f1a6613a4717bf6de47bc was fine for the normal
case, but please have pity on developers! Just like many multi-threaded
userland programs have an option to run single-threaded (usually for
debug purposes), the kernel should have this too.
I need a slowboot option, like the attached patch.
The patch is basically the reverse of your
9710794383ee5008d67f1a6613a4717bf6de47bc in a different way.
Jeff
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diff --git a/kernel/async.c b/kernel/async.c
index 968ef94..8c553ce 100644
--- a/kernel/async.c
+++ b/kernel/async.c
@@ -68,6 +68,7 @@ static LIST_HEAD(async_running);
static DEFINE_SPINLOCK(async_lock);
static int async_enabled = 0;
+static int async_disabled;
struct async_entry {
struct list_head list;
@@ -388,6 +389,11 @@ static int async_manager_thread(void *unused)
static int __init async_init(void)
{
+ if (async_disabled) {
+ async_enabled = 0;
+ return 0;
+ }
+
async_enabled =
!IS_ERR(kthread_run(async_manager_thread, NULL, "async/mgr"));
@@ -395,4 +401,12 @@ static int __init async_init(void)
return 0;
}
+static int __init setup_async(char *str)
+{
+ async_disabled = 1;
+ return 1;
+}
+
+__setup("slowboot", setup_async);
+
core_initcall(async_init);
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: How to completely disable async fastboot?
2009-04-16 1:31 ` Arjan van de Ven
2009-04-16 1:48 ` [PATCH] " Jeff Garzik
@ 2009-04-17 18:45 ` Stefan Richter
1 sibling, 0 replies; 4+ messages in thread
From: Stefan Richter @ 2009-04-17 18:45 UTC (permalink / raw)
To: Arjan van de Ven; +Cc: Jeff Garzik, LKML, Andrew Morton, David Howells
On 4/16/2009 3:31 AM, Arjan van de Ven wrote:
> On Wed, 15 Apr 2009 20:20:32 -0400
> Jeff Garzik <jeff@garzik.org> wrote:
>> > commit 9710794383ee5008d67f1a6613a4717bf6de47bc
...
>> not only changes a default, it completely removes the ability to turn
>> off async AFAICS.
>
> this is on the request of Andrew and others who want to be able to use
> these API's (soon) in an "forced offload" scenario.
Indeed, because the async API is a threadpool API.
However, 2.6.30-rc1 also gained David Howell's <linux/slow-work.h>, and
I for one am still wondering which one of these I'm going to use...
--
Stefan Richter
-=====-==--= -=-- =---=
http://arcgraph.de/sr/
^ permalink raw reply [flat|nested] 4+ messages in thread