D state after applying ps hang patch

D state after applying ps hang patch

[David Ford]

kernel 2.4.0-ac12

# ps -eo user,pid,args,wchan|egrep "imap|update|procmail"
root         7 [kupdate]        get_request_wait
david      627 imapd            get_request_wait
david      752 procmail -f linu down
david      761 procmail -f linu down
david      799 procmail -f linu down
david      854 procmail -f linu down
david      886 procmail -f linu down
david      847 imapd            get_request_wait
david     1079 procmail -f linu down
david     3280 imapd            interruptible_sleep_on_locked
david     3321 imapd            interruptible_sleep_on_locked

and the cpu load is artificially inflated to 9.17

-d

--
  There is a natural aristocracy among men. The grounds of this are virtue and talents. Thomas Jefferson
  The good thing about standards is that there are so many to choose from. Andrew S. Tanenbaum



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Re: D state after applying ps hang patch

[Jens Axboe]

On Mon, Jan 29 2001, David Ford wrote:
> kernel 2.4.0-ac12
> 
> # ps -eo user,pid,args,wchan|egrep "imap|update|procmail"
> root         7 [kupdate]        get_request_wait
> david      627 imapd            get_request_wait
> david      752 procmail -f linu down
> david      761 procmail -f linu down
> david      799 procmail -f linu down
> david      854 procmail -f linu down
> david      886 procmail -f linu down
> david      847 imapd            get_request_wait
> david     1079 procmail -f linu down
> david     3280 imapd            interruptible_sleep_on_locked
> david     3321 imapd            interruptible_sleep_on_locked
> 
> and the cpu load is artificially inflated to 9.17

Which patch specifically?

-- 
Jens Axboe
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Re: D state after applying ps hang patch

[David Ford]

The one LInus posted plus his addendum for the ll_rw_blk.
http://blue-labs.org/patches/ps-hang.patch

-d

Jens Axboe wrote:

> On Mon, Jan 29 2001, David Ford wrote:
> > kernel 2.4.0-ac12
> >
> > # ps -eo user,pid,args,wchan|egrep "imap|update|procmail"
> > root         7 [kupdate]        get_request_wait
> > david      627 imapd            get_request_wait
> > david      752 procmail -f linu down
> > david      761 procmail -f linu down
> > david      799 procmail -f linu down
> > david      854 procmail -f linu down
> > david      886 procmail -f linu down
> > david      847 imapd            get_request_wait
> > david     1079 procmail -f linu down
> > david     3280 imapd            interruptible_sleep_on_locked
> > david     3321 imapd            interruptible_sleep_on_locked
> >
> > and the cpu load is artificially inflated to 9.17
>
> Which patch specifically?

--
  There is a natural aristocracy among men. The grounds of this are virtue and talents. Thomas Jefferson
  The good thing about standards is that there are so many to choose from. Andrew S. Tanenbaum



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Re: D state after applying ps hang patch

[Jens Axboe]

On Sun, Jan 28 2001, David Ford wrote:
> The one LInus posted plus his addendum for the ll_rw_blk.
> http://blue-labs.org/patches/ps-hang.patch

You merged it wrong, Linus suggested to remove the entire

		if (!list_empty(&q->request_freelist[rw])) {
			blk_refill_freelist(q, rw);
			list_add(&req->table, &q->request_freelist[rw]);
			return;
		}

In fact, with the change you made the box can't possible survive
for very long - once the queue freelists are empty, you will
deadlock immediately.

Try this ll_rw_blk.c change instead, on top of pre11. Include
Linus' mm fixes of course.

--- /opt/kernel/linux-2.4.1-pre10/drivers/block/ll_rw_blk.c	Thu Jan 25 19:15:12 2001
+++ drivers/block/ll_rw_blk.c	Sun Jan 28 19:22:20 2001
@@ -633,6 +634,8 @@
 		if (!list_empty(&q->request_freelist[rw])) {
 			blk_refill_freelist(q, rw);
 			list_add(&req->table, &q->request_freelist[rw]);
+			if (waitqueue_active(&q->wait_for_request))
+				wake_up_nr(&q->wait_for_request, 2);
 			return;
 		}
 

-- 
Jens Axboe

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Re: D state after applying ps hang patch

[Jens Axboe]

On Mon, Jan 29 2001, Jens Axboe wrote:
> Try this ll_rw_blk.c change instead, on top of pre11. Include
> Linus' mm fixes of course.

On top of ac12 I mean, pre11 already has a different (but functional)
change.

-- 
Jens Axboe

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