* [PATCH] arm64: Reduce verbosity on SMP CPU stop @ 2016-04-15 10:24 Jan Glauber 2016-04-15 11:37 ` Will Deacon 0 siblings, 1 reply; 5+ messages in thread From: Jan Glauber @ 2016-04-15 10:24 UTC (permalink / raw) To: linux-arm-kernel When CPUs are stopped during an abnormal operation like panic for each CPU a line is printed and the stack trace is dumped. This information is only interesting for the aborting CPU and on systems with many CPUs it only makes it harder to debug if after the aborting CPU the log is flooded with data about all other CPUs too. Therefore remove the stack dump and printk of other CPUs and only print a single line that the other CPUs are going to be stopped. Signed-off-by: Jan Glauber <jglauber@cavium.com> --- arch/arm64/kernel/smp.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index b2d5f4e..e6c2eb1 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -770,14 +770,6 @@ static DEFINE_RAW_SPINLOCK(stop_lock); */ static void ipi_cpu_stop(unsigned int cpu) { - if (system_state == SYSTEM_BOOTING || - system_state == SYSTEM_RUNNING) { - raw_spin_lock(&stop_lock); - pr_crit("CPU%u: stopping\n", cpu); - dump_stack(); - raw_spin_unlock(&stop_lock); - } - set_cpu_online(cpu, false); local_irq_disable(); @@ -872,6 +864,9 @@ void smp_send_stop(void) cpumask_copy(&mask, cpu_online_mask); cpumask_clear_cpu(smp_processor_id(), &mask); + if (system_state == SYSTEM_BOOTING || + system_state == SYSTEM_RUNNING) + pr_crit("SMP: stopping secondary CPUs\n"); smp_cross_call(&mask, IPI_CPU_STOP); } -- 1.9.1 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH] arm64: Reduce verbosity on SMP CPU stop 2016-04-15 10:24 [PATCH] arm64: Reduce verbosity on SMP CPU stop Jan Glauber @ 2016-04-15 11:37 ` Will Deacon 2016-04-18 7:43 ` [PATCH v2] " Jan Glauber 0 siblings, 1 reply; 5+ messages in thread From: Will Deacon @ 2016-04-15 11:37 UTC (permalink / raw) To: linux-arm-kernel On Fri, Apr 15, 2016 at 12:24:36PM +0200, Jan Glauber wrote: > When CPUs are stopped during an abnormal operation like panic > for each CPU a line is printed and the stack trace is dumped. > > This information is only interesting for the aborting CPU > and on systems with many CPUs it only makes it harder to > debug if after the aborting CPU the log is flooded with data > about all other CPUs too. > > Therefore remove the stack dump and printk of other CPUs > and only print a single line that the other CPUs are going to be > stopped. > > Signed-off-by: Jan Glauber <jglauber@cavium.com> > --- > arch/arm64/kernel/smp.c | 11 +++-------- > 1 file changed, 3 insertions(+), 8 deletions(-) > > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index b2d5f4e..e6c2eb1 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -770,14 +770,6 @@ static DEFINE_RAW_SPINLOCK(stop_lock); > */ > static void ipi_cpu_stop(unsigned int cpu) > { > - if (system_state == SYSTEM_BOOTING || > - system_state == SYSTEM_RUNNING) { > - raw_spin_lock(&stop_lock); > - pr_crit("CPU%u: stopping\n", cpu); > - dump_stack(); > - raw_spin_unlock(&stop_lock); > - } > - > set_cpu_online(cpu, false); > > local_irq_disable(); > @@ -872,6 +864,9 @@ void smp_send_stop(void) > cpumask_copy(&mask, cpu_online_mask); > cpumask_clear_cpu(smp_processor_id(), &mask); > > + if (system_state == SYSTEM_BOOTING || > + system_state == SYSTEM_RUNNING) > + pr_crit("SMP: stopping secondary CPUs\n"); You can remove stop_lock altogether now, right? I also wonder whether it would be worth printing out which CPUs are still online in the case where we fail to stop all the secondaries? Will ^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2] arm64: Reduce verbosity on SMP CPU stop 2016-04-15 11:37 ` Will Deacon @ 2016-04-18 7:43 ` Jan Glauber 2016-04-18 12:19 ` Will Deacon 0 siblings, 1 reply; 5+ messages in thread From: Jan Glauber @ 2016-04-18 7:43 UTC (permalink / raw) To: linux-arm-kernel On Fri, Apr 15, 2016 at 12:37:06PM +0100, Will Deacon wrote: > You can remove stop_lock altogether now, right? I also wonder whether > it would be worth printing out which CPUs are still online in the case where > we fail to stop all the secondaries? Sorry, I've been a bit offline. Yes, the stop_lock can also be removed. How about below patch that prints the CPU ids for all CPUs that failed to stop? Jan -------------------------------- When CPUs are stopped during an abnormal operation like panic for each CPU a line is printed and the stack trace is dumped. This information is only interesting for the aborting CPU and on systems with many CPUs it only makes it harder to debug if after the aborting CPU the log is flooded with data about all other CPUs too. Therefore remove the stack dump and printk of other CPUs and only print a single line that the other CPUs are going to be stopped and, in case any CPUs remain online list them. Signed-off-by: Jan Glauber <jglauber@cavium.com> --- arch/arm64/kernel/smp.c | 16 +++++----------- 1 file changed, 5 insertions(+), 11 deletions(-) diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index b2d5f4e..29f4e37 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -763,21 +763,11 @@ void arch_irq_work_raise(void) } #endif -static DEFINE_RAW_SPINLOCK(stop_lock); - /* * ipi_cpu_stop - handle IPI from smp_send_stop() */ static void ipi_cpu_stop(unsigned int cpu) { - if (system_state == SYSTEM_BOOTING || - system_state == SYSTEM_RUNNING) { - raw_spin_lock(&stop_lock); - pr_crit("CPU%u: stopping\n", cpu); - dump_stack(); - raw_spin_unlock(&stop_lock); - } - set_cpu_online(cpu, false); local_irq_disable(); @@ -872,6 +862,9 @@ void smp_send_stop(void) cpumask_copy(&mask, cpu_online_mask); cpumask_clear_cpu(smp_processor_id(), &mask); + if (system_state == SYSTEM_BOOTING || + system_state == SYSTEM_RUNNING) + pr_crit("SMP: stopping secondary CPUs\n"); smp_cross_call(&mask, IPI_CPU_STOP); } @@ -881,7 +874,8 @@ void smp_send_stop(void) udelay(1); if (num_online_cpus() > 1) - pr_warning("SMP: failed to stop secondary CPUs\n"); + pr_warning("SMP: failed to stop secondary CPUs %*pbl\n", + cpumask_pr_args(cpu_online_mask)); } /* -- 1.9.1 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH v2] arm64: Reduce verbosity on SMP CPU stop 2016-04-18 7:43 ` [PATCH v2] " Jan Glauber @ 2016-04-18 12:19 ` Will Deacon 2016-04-18 13:17 ` Jan Glauber 0 siblings, 1 reply; 5+ messages in thread From: Will Deacon @ 2016-04-18 12:19 UTC (permalink / raw) To: linux-arm-kernel On Mon, Apr 18, 2016 at 09:43:33AM +0200, Jan Glauber wrote: > On Fri, Apr 15, 2016 at 12:37:06PM +0100, Will Deacon wrote: > > You can remove stop_lock altogether now, right? I also wonder whether > > it would be worth printing out which CPUs are still online in the case where > > we fail to stop all the secondaries? > > Sorry, I've been a bit offline. Yes, the stop_lock can also be removed. > > How about below patch that prints the CPU ids for all CPUs that failed > to stop? Yeah, this looks better, thanks. We might want to clear the "stopper" CPU from the mask, but it's hard to really care that much. Will > > Jan > > -------------------------------- > > When CPUs are stopped during an abnormal operation like panic > for each CPU a line is printed and the stack trace is dumped. > > This information is only interesting for the aborting CPU > and on systems with many CPUs it only makes it harder to > debug if after the aborting CPU the log is flooded with data > about all other CPUs too. > > Therefore remove the stack dump and printk of other CPUs > and only print a single line that the other CPUs are going to be > stopped and, in case any CPUs remain online list them. > > Signed-off-by: Jan Glauber <jglauber@cavium.com> > --- > arch/arm64/kernel/smp.c | 16 +++++----------- > 1 file changed, 5 insertions(+), 11 deletions(-) > > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index b2d5f4e..29f4e37 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -763,21 +763,11 @@ void arch_irq_work_raise(void) > } > #endif > > -static DEFINE_RAW_SPINLOCK(stop_lock); > - > /* > * ipi_cpu_stop - handle IPI from smp_send_stop() > */ > static void ipi_cpu_stop(unsigned int cpu) > { > - if (system_state == SYSTEM_BOOTING || > - system_state == SYSTEM_RUNNING) { > - raw_spin_lock(&stop_lock); > - pr_crit("CPU%u: stopping\n", cpu); > - dump_stack(); > - raw_spin_unlock(&stop_lock); > - } > - > set_cpu_online(cpu, false); > > local_irq_disable(); > @@ -872,6 +862,9 @@ void smp_send_stop(void) > cpumask_copy(&mask, cpu_online_mask); > cpumask_clear_cpu(smp_processor_id(), &mask); > > + if (system_state == SYSTEM_BOOTING || > + system_state == SYSTEM_RUNNING) > + pr_crit("SMP: stopping secondary CPUs\n"); > smp_cross_call(&mask, IPI_CPU_STOP); > } > > @@ -881,7 +874,8 @@ void smp_send_stop(void) > udelay(1); > > if (num_online_cpus() > 1) > - pr_warning("SMP: failed to stop secondary CPUs\n"); > + pr_warning("SMP: failed to stop secondary CPUs %*pbl\n", > + cpumask_pr_args(cpu_online_mask)); > } > > /* > -- > 1.9.1 > ^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2] arm64: Reduce verbosity on SMP CPU stop 2016-04-18 12:19 ` Will Deacon @ 2016-04-18 13:17 ` Jan Glauber 0 siblings, 0 replies; 5+ messages in thread From: Jan Glauber @ 2016-04-18 13:17 UTC (permalink / raw) To: linux-arm-kernel On Mon, Apr 18, 2016 at 01:19:31PM +0100, Will Deacon wrote: > On Mon, Apr 18, 2016 at 09:43:33AM +0200, Jan Glauber wrote: > > On Fri, Apr 15, 2016 at 12:37:06PM +0100, Will Deacon wrote: > > > You can remove stop_lock altogether now, right? I also wonder whether > > > it would be worth printing out which CPUs are still online in the case where > > > we fail to stop all the secondaries? > > > > Sorry, I've been a bit offline. Yes, the stop_lock can also be removed. > > > > How about below patch that prints the CPU ids for all CPUs that failed > > to stop? > > Yeah, this looks better, thanks. We might want to clear the "stopper" > CPU from the mask, but it's hard to really care that much. Then let's not do it, the fact that "the CPU that executes this code is also still online" is not too wrong... Jan > Will > > > > > Jan > > > > -------------------------------- > > > > When CPUs are stopped during an abnormal operation like panic > > for each CPU a line is printed and the stack trace is dumped. > > > > This information is only interesting for the aborting CPU > > and on systems with many CPUs it only makes it harder to > > debug if after the aborting CPU the log is flooded with data > > about all other CPUs too. > > > > Therefore remove the stack dump and printk of other CPUs > > and only print a single line that the other CPUs are going to be > > stopped and, in case any CPUs remain online list them. > > > > Signed-off-by: Jan Glauber <jglauber@cavium.com> > > --- > > arch/arm64/kernel/smp.c | 16 +++++----------- > > 1 file changed, 5 insertions(+), 11 deletions(-) > > > > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > > index b2d5f4e..29f4e37 100644 > > --- a/arch/arm64/kernel/smp.c > > +++ b/arch/arm64/kernel/smp.c > > @@ -763,21 +763,11 @@ void arch_irq_work_raise(void) > > } > > #endif > > > > -static DEFINE_RAW_SPINLOCK(stop_lock); > > - > > /* > > * ipi_cpu_stop - handle IPI from smp_send_stop() > > */ > > static void ipi_cpu_stop(unsigned int cpu) > > { > > - if (system_state == SYSTEM_BOOTING || > > - system_state == SYSTEM_RUNNING) { > > - raw_spin_lock(&stop_lock); > > - pr_crit("CPU%u: stopping\n", cpu); > > - dump_stack(); > > - raw_spin_unlock(&stop_lock); > > - } > > - > > set_cpu_online(cpu, false); > > > > local_irq_disable(); > > @@ -872,6 +862,9 @@ void smp_send_stop(void) > > cpumask_copy(&mask, cpu_online_mask); > > cpumask_clear_cpu(smp_processor_id(), &mask); > > > > + if (system_state == SYSTEM_BOOTING || > > + system_state == SYSTEM_RUNNING) > > + pr_crit("SMP: stopping secondary CPUs\n"); > > smp_cross_call(&mask, IPI_CPU_STOP); > > } > > > > @@ -881,7 +874,8 @@ void smp_send_stop(void) > > udelay(1); > > > > if (num_online_cpus() > 1) > > - pr_warning("SMP: failed to stop secondary CPUs\n"); > > + pr_warning("SMP: failed to stop secondary CPUs %*pbl\n", > > + cpumask_pr_args(cpu_online_mask)); > > } > > > > /* > > -- > > 1.9.1 > > ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2016-04-18 13:17 UTC | newest] Thread overview: 5+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2016-04-15 10:24 [PATCH] arm64: Reduce verbosity on SMP CPU stop Jan Glauber 2016-04-15 11:37 ` Will Deacon 2016-04-18 7:43 ` [PATCH v2] " Jan Glauber 2016-04-18 12:19 ` Will Deacon 2016-04-18 13:17 ` Jan Glauber
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