Messages in this thread Patch in this message | | | From | Diwakar Tundlam <> | Date | Wed, 9 May 2012 11:55:23 -0700 | Subject | RE: [PATCH] sched: Make nr_uninterruptible count a signed value |
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>> - P(nr_uninterruptible); >> + P((signed long)nr_uninterruptible);
I thought of it too, but it won't compile because the P macro expands to dereferencing rq->nr_uninterruptible, so with your change, it will show up as rq->(signed long)nr_uninterruptible which is a syntax error.
--Diwakar.
-----Original Message----- From: Michael Wang [mailto:wangyun@linux.vnet.ibm.com] Sent: Wednesday, May 09, 2012 12:49 AM To: Diwakar Tundlam Cc: 'Peter Zijlstra'; 'Ingo Molnar'; 'David Rientjes'; 'linux-kernel@vger.kernel.org'; Peter De Schrijver Subject: Re: [PATCH] sched: Make nr_uninterruptible count a signed value
On 05/09/2012 06:46 AM, Diwakar Tundlam wrote:
>> No that's right. nr_uninterruptible counts the number of tasks in >> uninterruptible sleep, so deactivate_task puts a task to sleep, so we >> need to increment the number of sleeping tasks, activate_task wakes a >> task up so we need to decrement the number of sleeping tasks. > > Yep, I looked at the code for task_contributes_to_load() and I understand what it is all about. > The ++ and -- are correct, I see it now. > > On the -ve values, strangely inspite of %Ld in the print statement, in my kernel, I see high unsigned values instead of -ve values for nr_uninterruptible. > > But the sum is always 0, though. > > Maybe it is an artifact of 32-bit machine displaying 64-bit print format. > An (unsigned long)(-24) promoted to (signed long long) ends up as 4294967272. > As seen in my output of sched_debug.
This may do some help.
Regards, Michael Wang --- kernel/sched/debug.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 09acaa1..ab9d53f 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -270,7 +270,7 @@ static void print_cpu(struct seq_file *m, int cpu) rq->load.weight); P(nr_switches); P(nr_load_updates); - P(nr_uninterruptible); + P((signed long)nr_uninterruptible); PN(next_balance); P(curr->pid); PN(clock); -- 1.7.4.1
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