Re: [PATCH] sched: change nr_uninterruptible to be signed
On Fri, Nov 27, 2015 at 12:09:44PM +0800, yalin wang wrote: > nr_uninterruptible will be negative during running, > this happened when dequeue a TASK_UNINTERRUPTIBLE task > from rq1 and then wake up the task and queue it to rq2, > then rq2->nr_uninterruptible-- will reuslt in negative value > sometimes. Why!? Aren't isn't signed stuff more likely affected by over/underflow muck? I'd be more inclined to remove the signed muck altogether like: That relies on C having defined overflow semantics for unsigned types and the (hard) assumption that the hardware uses 2s-complement (which the kernel assumes in many many places already). diff --git a/kernel/sched/loadavg.c b/kernel/sched/loadavg.c index ef7159012cf3..62cff13ed120 100644 --- a/kernel/sched/loadavg.c +++ b/kernel/sched/loadavg.c @@ -80,13 +80,14 @@ void get_avenrun(unsigned long *loads, unsigned long offset, int shift) long calc_load_fold_active(struct rq *this_rq) { - long nr_active, delta = 0; + unsigned long nr_active; + long delta = 0; nr_active = this_rq->nr_running; - nr_active += (long)this_rq->nr_uninterruptible; + nr_active += this_rq->nr_uninterruptible; if (nr_active != this_rq->calc_load_active) { - delta = nr_active - this_rq->calc_load_active; + delta = (long)(nr_active - this_rq->calc_load_active); this_rq->calc_load_active = nr_active; } diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 2eb2002aa336..2f9b4ce759dc 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -652,7 +652,7 @@ struct rq { /* calc_load related fields */ unsigned long calc_load_update; - long calc_load_active; + unsigned long calc_load_active; #ifdef CONFIG_SCHED_HRTICK #ifdef CONFIG_SMP -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] sched: change nr_uninterruptible to be signed
On Fri, Nov 27, 2015 at 12:09:44PM +0800, yalin wang wrote: > nr_uninterruptible will be negative during running, > this happened when dequeue a TASK_UNINTERRUPTIBLE task > from rq1 and then wake up the task and queue it to rq2, > then rq2->nr_uninterruptible-- will reuslt in negative value > sometimes. Why!? Aren't isn't signed stuff more likely affected by over/underflow muck? I'd be more inclined to remove the signed muck altogether like: That relies on C having defined overflow semantics for unsigned types and the (hard) assumption that the hardware uses 2s-complement (which the kernel assumes in many many places already). diff --git a/kernel/sched/loadavg.c b/kernel/sched/loadavg.c index ef7159012cf3..62cff13ed120 100644 --- a/kernel/sched/loadavg.c +++ b/kernel/sched/loadavg.c @@ -80,13 +80,14 @@ void get_avenrun(unsigned long *loads, unsigned long offset, int shift) long calc_load_fold_active(struct rq *this_rq) { - long nr_active, delta = 0; + unsigned long nr_active; + long delta = 0; nr_active = this_rq->nr_running; - nr_active += (long)this_rq->nr_uninterruptible; + nr_active += this_rq->nr_uninterruptible; if (nr_active != this_rq->calc_load_active) { - delta = nr_active - this_rq->calc_load_active; + delta = (long)(nr_active - this_rq->calc_load_active); this_rq->calc_load_active = nr_active; } diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 2eb2002aa336..2f9b4ce759dc 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -652,7 +652,7 @@ struct rq { /* calc_load related fields */ unsigned long calc_load_update; - long calc_load_active; + unsigned long calc_load_active; #ifdef CONFIG_SCHED_HRTICK #ifdef CONFIG_SMP -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH] sched: change nr_uninterruptible to be signed
nr_uninterruptible will be negative during running, this happened when dequeue a TASK_UNINTERRUPTIBLE task from rq1 and then wake up the task and queue it to rq2, then rq2->nr_uninterruptible-- will reuslt in negative value sometimes. Signed-off-by: yalin wang --- kernel/sched/loadavg.c | 2 +- kernel/sched/sched.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/loadavg.c b/kernel/sched/loadavg.c index ef71590..39504c6 100644 --- a/kernel/sched/loadavg.c +++ b/kernel/sched/loadavg.c @@ -83,7 +83,7 @@ long calc_load_fold_active(struct rq *this_rq) long nr_active, delta = 0; nr_active = this_rq->nr_running; - nr_active += (long)this_rq->nr_uninterruptible; + nr_active += this_rq->nr_uninterruptible; if (nr_active != this_rq->calc_load_active) { delta = nr_active - this_rq->calc_load_active; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 84d4879..7b5f67b 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -605,7 +605,7 @@ struct rq { * one CPU and if it got migrated afterwards it may decrease * it on another CPU. Always updated under the runqueue lock: */ - unsigned long nr_uninterruptible; + long nr_uninterruptible; struct task_struct *curr, *idle, *stop; unsigned long next_balance; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH] sched: change nr_uninterruptible to be signed
nr_uninterruptible will be negative during running, this happened when dequeue a TASK_UNINTERRUPTIBLE task from rq1 and then wake up the task and queue it to rq2, then rq2->nr_uninterruptible-- will reuslt in negative value sometimes. Signed-off-by: yalin wang--- kernel/sched/loadavg.c | 2 +- kernel/sched/sched.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/loadavg.c b/kernel/sched/loadavg.c index ef71590..39504c6 100644 --- a/kernel/sched/loadavg.c +++ b/kernel/sched/loadavg.c @@ -83,7 +83,7 @@ long calc_load_fold_active(struct rq *this_rq) long nr_active, delta = 0; nr_active = this_rq->nr_running; - nr_active += (long)this_rq->nr_uninterruptible; + nr_active += this_rq->nr_uninterruptible; if (nr_active != this_rq->calc_load_active) { delta = nr_active - this_rq->calc_load_active; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 84d4879..7b5f67b 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -605,7 +605,7 @@ struct rq { * one CPU and if it got migrated afterwards it may decrease * it on another CPU. Always updated under the runqueue lock: */ - unsigned long nr_uninterruptible; + long nr_uninterruptible; struct task_struct *curr, *idle, *stop; unsigned long next_balance; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/