* [PATCH v3] rcu/cpu_stall_cputime: fix the hardirq count for x86 architecture
@ 2025-02-16 8:41 Yongliang Gao
2025-02-17 2:29 ` Boqun Feng
0 siblings, 1 reply; 3+ messages in thread
From: Yongliang Gao @ 2025-02-16 8:41 UTC (permalink / raw)
To: Neeraj.Upadhyay, paulmck, frederic, thunder.leizhen
Cc: frankjpliu, kernelxing, rcu, linux-kernel, Yongliang Gao,
kernel test robot
From: Yongliang Gao <leonylgao@tencent.com>
When counting the number of hardirqs in the x86 architecture,
it is essential to add arch_irq_stat_cpu to ensure accuracy.
For example, a CPU loop within the rcu_read_lock function.
Before:
[ 70.910184] rcu: INFO: rcu_preempt self-detected stall on CPU
[ 70.910436] rcu: 3-....: (4999 ticks this GP) idle=***
[ 70.910711] rcu: hardirqs softirqs csw/system
[ 70.910870] rcu: number: 0 657 0
[ 70.911024] rcu: cputime: 0 0 2498 ==> 2498(ms)
[ 70.911278] rcu: (t=5001 jiffies g=3677 q=29 ncpus=8)
After:
[ 68.046132] rcu: INFO: rcu_preempt self-detected stall on CPU
[ 68.046354] rcu: 2-....: (4999 ticks this GP) idle=***
[ 68.046628] rcu: hardirqs softirqs csw/system
[ 68.046793] rcu: number: 2498 663 0
[ 68.046951] rcu: cputime: 0 0 2496 ==> 2496(ms)
[ 68.047244] rcu: (t=5000 jiffies g=3825 q=4 ncpus=8)
Fixes: be42f00b73a0 ("rcu: Add RCU stall diagnosis information")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202501090842.SfI6QPGS-lkp@intel.com/
Signed-off-by: Yongliang Gao <leonylgao@tencent.com>
Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>
---
Changes from v2:
- Add Reviewed-by 'Neeraj Upadhyay' information
- Link to v2: https://lore.kernel.org/all/20250109024652.1342595-1-leonylgao@gmail.com
Changes from v1:
- Fix compilation error when using arm64-allnoconfig/riscv-randconfig. [kernel test robot]
- Link to v1: https://lore.kernel.org/r/20250108065716.2888148-1-leonylgao%40gmail.com
---
---
kernel/rcu/tree.c | 10 +++++++---
kernel/rcu/tree.h | 2 +-
kernel/rcu/tree_stall.h | 4 ++--
3 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 475f31deed14..a0dab5923d03 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -781,6 +781,10 @@ static int rcu_watching_snap_save(struct rcu_data *rdp)
return 0;
}
+#ifndef arch_irq_stat_cpu
+#define arch_irq_stat_cpu(cpu) 0
+#endif
+
/*
* Returns positive if the specified CPU has passed through a quiescent state
* by virtue of being in or having passed through an dynticks idle state since
@@ -916,9 +920,9 @@ static int rcu_watching_snap_recheck(struct rcu_data *rdp)
rsrp->cputime_irq = kcpustat_field(kcsp, CPUTIME_IRQ, cpu);
rsrp->cputime_softirq = kcpustat_field(kcsp, CPUTIME_SOFTIRQ, cpu);
rsrp->cputime_system = kcpustat_field(kcsp, CPUTIME_SYSTEM, cpu);
- rsrp->nr_hardirqs = kstat_cpu_irqs_sum(rdp->cpu);
- rsrp->nr_softirqs = kstat_cpu_softirqs_sum(rdp->cpu);
- rsrp->nr_csw = nr_context_switches_cpu(rdp->cpu);
+ rsrp->nr_hardirqs = kstat_cpu_irqs_sum(cpu) + arch_irq_stat_cpu(cpu);
+ rsrp->nr_softirqs = kstat_cpu_softirqs_sum(cpu);
+ rsrp->nr_csw = nr_context_switches_cpu(cpu);
rsrp->jiffies = jiffies;
rsrp->gp_seq = rdp->gp_seq;
}
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index a9a811d9d7a3..1bba2225e744 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -168,7 +168,7 @@ struct rcu_snap_record {
u64 cputime_irq; /* Accumulated cputime of hard irqs */
u64 cputime_softirq;/* Accumulated cputime of soft irqs */
u64 cputime_system; /* Accumulated cputime of kernel tasks */
- unsigned long nr_hardirqs; /* Accumulated number of hard irqs */
+ u64 nr_hardirqs; /* Accumulated number of hard irqs */
unsigned int nr_softirqs; /* Accumulated number of soft irqs */
unsigned long long nr_csw; /* Accumulated number of task switches */
unsigned long jiffies; /* Track jiffies value */
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 925fcdad5dea..56b21219442b 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -435,8 +435,8 @@ static void print_cpu_stat_info(int cpu)
rsr.cputime_system = kcpustat_field(kcsp, CPUTIME_SYSTEM, cpu);
pr_err("\t hardirqs softirqs csw/system\n");
- pr_err("\t number: %8ld %10d %12lld\n",
- kstat_cpu_irqs_sum(cpu) - rsrp->nr_hardirqs,
+ pr_err("\t number: %8lld %10d %12lld\n",
+ kstat_cpu_irqs_sum(cpu) + arch_irq_stat_cpu(cpu) - rsrp->nr_hardirqs,
kstat_cpu_softirqs_sum(cpu) - rsrp->nr_softirqs,
nr_context_switches_cpu(cpu) - rsrp->nr_csw);
pr_err("\tcputime: %8lld %10lld %12lld ==> %d(ms)\n",
--
2.39.3
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH v3] rcu/cpu_stall_cputime: fix the hardirq count for x86 architecture 2025-02-16 8:41 [PATCH v3] rcu/cpu_stall_cputime: fix the hardirq count for x86 architecture Yongliang Gao @ 2025-02-17 2:29 ` Boqun Feng 2025-03-05 16:43 ` Boqun Feng 0 siblings, 1 reply; 3+ messages in thread From: Boqun Feng @ 2025-02-17 2:29 UTC (permalink / raw) To: Yongliang Gao Cc: Neeraj.Upadhyay, paulmck, frederic, thunder.leizhen, frankjpliu, kernelxing, rcu, linux-kernel, Yongliang Gao, kernel test robot, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86, H. Peter Anvin Hi Yongliang, On Sun, Feb 16, 2025 at 04:41:09PM +0800, Yongliang Gao wrote: > From: Yongliang Gao <leonylgao@tencent.com> > > When counting the number of hardirqs in the x86 architecture, > it is essential to add arch_irq_stat_cpu to ensure accuracy. > > For example, a CPU loop within the rcu_read_lock function. > > Before: > [ 70.910184] rcu: INFO: rcu_preempt self-detected stall on CPU > [ 70.910436] rcu: 3-....: (4999 ticks this GP) idle=*** > [ 70.910711] rcu: hardirqs softirqs csw/system > [ 70.910870] rcu: number: 0 657 0 > [ 70.911024] rcu: cputime: 0 0 2498 ==> 2498(ms) > [ 70.911278] rcu: (t=5001 jiffies g=3677 q=29 ncpus=8) > > After: > [ 68.046132] rcu: INFO: rcu_preempt self-detected stall on CPU > [ 68.046354] rcu: 2-....: (4999 ticks this GP) idle=*** > [ 68.046628] rcu: hardirqs softirqs csw/system > [ 68.046793] rcu: number: 2498 663 0 > [ 68.046951] rcu: cputime: 0 0 2496 ==> 2496(ms) > [ 68.047244] rcu: (t=5000 jiffies g=3825 q=4 ncpus=8) > > Fixes: be42f00b73a0 ("rcu: Add RCU stall diagnosis information") > Reported-by: kernel test robot <lkp@intel.com> > Closes: https://lore.kernel.org/oe-kbuild-all/202501090842.SfI6QPGS-lkp@intel.com/ > Signed-off-by: Yongliang Gao <leonylgao@tencent.com> > Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com> > Thank you for the patch, I have one minor question to x86 maintainers (Cced): does it make sense to fold the sum of arch_irq_stat_cpu() into kstat_cpu_irqs_sum()? Regards, Boqun > --- > Changes from v2: > - Add Reviewed-by 'Neeraj Upadhyay' information > - Link to v2: https://lore.kernel.org/all/20250109024652.1342595-1-leonylgao@gmail.com > Changes from v1: > - Fix compilation error when using arm64-allnoconfig/riscv-randconfig. [kernel test robot] > - Link to v1: https://lore.kernel.org/r/20250108065716.2888148-1-leonylgao%40gmail.com > --- > --- > kernel/rcu/tree.c | 10 +++++++--- > kernel/rcu/tree.h | 2 +- > kernel/rcu/tree_stall.h | 4 ++-- > 3 files changed, 10 insertions(+), 6 deletions(-) > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 475f31deed14..a0dab5923d03 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -781,6 +781,10 @@ static int rcu_watching_snap_save(struct rcu_data *rdp) > return 0; > } > > +#ifndef arch_irq_stat_cpu > +#define arch_irq_stat_cpu(cpu) 0 > +#endif > + > /* > * Returns positive if the specified CPU has passed through a quiescent state > * by virtue of being in or having passed through an dynticks idle state since > @@ -916,9 +920,9 @@ static int rcu_watching_snap_recheck(struct rcu_data *rdp) > rsrp->cputime_irq = kcpustat_field(kcsp, CPUTIME_IRQ, cpu); > rsrp->cputime_softirq = kcpustat_field(kcsp, CPUTIME_SOFTIRQ, cpu); > rsrp->cputime_system = kcpustat_field(kcsp, CPUTIME_SYSTEM, cpu); > - rsrp->nr_hardirqs = kstat_cpu_irqs_sum(rdp->cpu); > - rsrp->nr_softirqs = kstat_cpu_softirqs_sum(rdp->cpu); > - rsrp->nr_csw = nr_context_switches_cpu(rdp->cpu); > + rsrp->nr_hardirqs = kstat_cpu_irqs_sum(cpu) + arch_irq_stat_cpu(cpu); > + rsrp->nr_softirqs = kstat_cpu_softirqs_sum(cpu); > + rsrp->nr_csw = nr_context_switches_cpu(cpu); > rsrp->jiffies = jiffies; > rsrp->gp_seq = rdp->gp_seq; > } > diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h > index a9a811d9d7a3..1bba2225e744 100644 > --- a/kernel/rcu/tree.h > +++ b/kernel/rcu/tree.h > @@ -168,7 +168,7 @@ struct rcu_snap_record { > u64 cputime_irq; /* Accumulated cputime of hard irqs */ > u64 cputime_softirq;/* Accumulated cputime of soft irqs */ > u64 cputime_system; /* Accumulated cputime of kernel tasks */ > - unsigned long nr_hardirqs; /* Accumulated number of hard irqs */ > + u64 nr_hardirqs; /* Accumulated number of hard irqs */ > unsigned int nr_softirqs; /* Accumulated number of soft irqs */ > unsigned long long nr_csw; /* Accumulated number of task switches */ > unsigned long jiffies; /* Track jiffies value */ > diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h > index 925fcdad5dea..56b21219442b 100644 > --- a/kernel/rcu/tree_stall.h > +++ b/kernel/rcu/tree_stall.h > @@ -435,8 +435,8 @@ static void print_cpu_stat_info(int cpu) > rsr.cputime_system = kcpustat_field(kcsp, CPUTIME_SYSTEM, cpu); > > pr_err("\t hardirqs softirqs csw/system\n"); > - pr_err("\t number: %8ld %10d %12lld\n", > - kstat_cpu_irqs_sum(cpu) - rsrp->nr_hardirqs, > + pr_err("\t number: %8lld %10d %12lld\n", > + kstat_cpu_irqs_sum(cpu) + arch_irq_stat_cpu(cpu) - rsrp->nr_hardirqs, > kstat_cpu_softirqs_sum(cpu) - rsrp->nr_softirqs, > nr_context_switches_cpu(cpu) - rsrp->nr_csw); > pr_err("\tcputime: %8lld %10lld %12lld ==> %d(ms)\n", > -- > 2.39.3 > > ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3] rcu/cpu_stall_cputime: fix the hardirq count for x86 architecture 2025-02-17 2:29 ` Boqun Feng @ 2025-03-05 16:43 ` Boqun Feng 0 siblings, 0 replies; 3+ messages in thread From: Boqun Feng @ 2025-03-05 16:43 UTC (permalink / raw) To: Yongliang Gao Cc: Neeraj.Upadhyay, paulmck, frederic, thunder.leizhen, frankjpliu, kernelxing, rcu, linux-kernel, Yongliang Gao, kernel test robot, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86, H. Peter Anvin On Sun, Feb 16, 2025 at 06:29:54PM -0800, Boqun Feng wrote: > Hi Yongliang, > > On Sun, Feb 16, 2025 at 04:41:09PM +0800, Yongliang Gao wrote: > > From: Yongliang Gao <leonylgao@tencent.com> > > > > When counting the number of hardirqs in the x86 architecture, > > it is essential to add arch_irq_stat_cpu to ensure accuracy. > > > > For example, a CPU loop within the rcu_read_lock function. > > > > Before: > > [ 70.910184] rcu: INFO: rcu_preempt self-detected stall on CPU > > [ 70.910436] rcu: 3-....: (4999 ticks this GP) idle=*** > > [ 70.910711] rcu: hardirqs softirqs csw/system > > [ 70.910870] rcu: number: 0 657 0 > > [ 70.911024] rcu: cputime: 0 0 2498 ==> 2498(ms) > > [ 70.911278] rcu: (t=5001 jiffies g=3677 q=29 ncpus=8) > > > > After: > > [ 68.046132] rcu: INFO: rcu_preempt self-detected stall on CPU > > [ 68.046354] rcu: 2-....: (4999 ticks this GP) idle=*** > > [ 68.046628] rcu: hardirqs softirqs csw/system > > [ 68.046793] rcu: number: 2498 663 0 > > [ 68.046951] rcu: cputime: 0 0 2496 ==> 2496(ms) > > [ 68.047244] rcu: (t=5000 jiffies g=3825 q=4 ncpus=8) > > > > Fixes: be42f00b73a0 ("rcu: Add RCU stall diagnosis information") > > Reported-by: kernel test robot <lkp@intel.com> > > Closes: https://lore.kernel.org/oe-kbuild-all/202501090842.SfI6QPGS-lkp@intel.com/ > > Signed-off-by: Yongliang Gao <leonylgao@tencent.com> > > Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com> > > > > Thank you for the patch, I have one minor question to x86 maintainers > (Cced): does it make sense to fold the sum of arch_irq_stat_cpu() into > kstat_cpu_irqs_sum()? > Queued for further tests and reviews, but my question for x86 maintainers remains ;-) Regards, Boqun > Regards, > Boqun > > > --- > > Changes from v2: > > - Add Reviewed-by 'Neeraj Upadhyay' information > > - Link to v2: https://lore.kernel.org/all/20250109024652.1342595-1-leonylgao@gmail.com > > Changes from v1: > > - Fix compilation error when using arm64-allnoconfig/riscv-randconfig. [kernel test robot] > > - Link to v1: https://lore.kernel.org/r/20250108065716.2888148-1-leonylgao%40gmail.com > > --- > > --- > > kernel/rcu/tree.c | 10 +++++++--- > > kernel/rcu/tree.h | 2 +- > > kernel/rcu/tree_stall.h | 4 ++-- > > 3 files changed, 10 insertions(+), 6 deletions(-) > > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > > index 475f31deed14..a0dab5923d03 100644 > > --- a/kernel/rcu/tree.c > > +++ b/kernel/rcu/tree.c > > @@ -781,6 +781,10 @@ static int rcu_watching_snap_save(struct rcu_data *rdp) > > return 0; > > } > > > > +#ifndef arch_irq_stat_cpu > > +#define arch_irq_stat_cpu(cpu) 0 > > +#endif > > + > > /* > > * Returns positive if the specified CPU has passed through a quiescent state > > * by virtue of being in or having passed through an dynticks idle state since > > @@ -916,9 +920,9 @@ static int rcu_watching_snap_recheck(struct rcu_data *rdp) > > rsrp->cputime_irq = kcpustat_field(kcsp, CPUTIME_IRQ, cpu); > > rsrp->cputime_softirq = kcpustat_field(kcsp, CPUTIME_SOFTIRQ, cpu); > > rsrp->cputime_system = kcpustat_field(kcsp, CPUTIME_SYSTEM, cpu); > > - rsrp->nr_hardirqs = kstat_cpu_irqs_sum(rdp->cpu); > > - rsrp->nr_softirqs = kstat_cpu_softirqs_sum(rdp->cpu); > > - rsrp->nr_csw = nr_context_switches_cpu(rdp->cpu); > > + rsrp->nr_hardirqs = kstat_cpu_irqs_sum(cpu) + arch_irq_stat_cpu(cpu); > > + rsrp->nr_softirqs = kstat_cpu_softirqs_sum(cpu); > > + rsrp->nr_csw = nr_context_switches_cpu(cpu); > > rsrp->jiffies = jiffies; > > rsrp->gp_seq = rdp->gp_seq; > > } > > diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h > > index a9a811d9d7a3..1bba2225e744 100644 > > --- a/kernel/rcu/tree.h > > +++ b/kernel/rcu/tree.h > > @@ -168,7 +168,7 @@ struct rcu_snap_record { > > u64 cputime_irq; /* Accumulated cputime of hard irqs */ > > u64 cputime_softirq;/* Accumulated cputime of soft irqs */ > > u64 cputime_system; /* Accumulated cputime of kernel tasks */ > > - unsigned long nr_hardirqs; /* Accumulated number of hard irqs */ > > + u64 nr_hardirqs; /* Accumulated number of hard irqs */ > > unsigned int nr_softirqs; /* Accumulated number of soft irqs */ > > unsigned long long nr_csw; /* Accumulated number of task switches */ > > unsigned long jiffies; /* Track jiffies value */ > > diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h > > index 925fcdad5dea..56b21219442b 100644 > > --- a/kernel/rcu/tree_stall.h > > +++ b/kernel/rcu/tree_stall.h > > @@ -435,8 +435,8 @@ static void print_cpu_stat_info(int cpu) > > rsr.cputime_system = kcpustat_field(kcsp, CPUTIME_SYSTEM, cpu); > > > > pr_err("\t hardirqs softirqs csw/system\n"); > > - pr_err("\t number: %8ld %10d %12lld\n", > > - kstat_cpu_irqs_sum(cpu) - rsrp->nr_hardirqs, > > + pr_err("\t number: %8lld %10d %12lld\n", > > + kstat_cpu_irqs_sum(cpu) + arch_irq_stat_cpu(cpu) - rsrp->nr_hardirqs, > > kstat_cpu_softirqs_sum(cpu) - rsrp->nr_softirqs, > > nr_context_switches_cpu(cpu) - rsrp->nr_csw); > > pr_err("\tcputime: %8lld %10lld %12lld ==> %d(ms)\n", > > -- > > 2.39.3 > > > > > ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2025-03-05 16:43 UTC | newest] Thread overview: 3+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2025-02-16 8:41 [PATCH v3] rcu/cpu_stall_cputime: fix the hardirq count for x86 architecture Yongliang Gao 2025-02-17 2:29 ` Boqun Feng 2025-03-05 16:43 ` Boqun Feng
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