* cpu hotplug: possible_cpus broken (again?) next-20130607
@ 2013-06-11 21:51 Dave Hansen
2013-06-11 22:05 ` Rafael J. Wysocki
0 siblings, 1 reply; 12+ messages in thread
From: Dave Hansen @ 2013-06-11 21:51 UTC (permalink / raw)
To: Toshi Kani, LKML, rjw
possible_cpus looks broken again. I'm booting with:
maxcpus=10 possible_cpus=160
But I only get 0-9 in sysfs:
> # ls /sys/devices/system/cpu/
> cpu0 cpu2 cpu4 cpu6 cpu8 cpufreq kernel_max offline possible probe uevent
> cpu1 cpu3 cpu5 cpu7 cpu9 cpuidle modalias online present release
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: cpu hotplug: possible_cpus broken (again?) next-20130607 2013-06-11 21:51 cpu hotplug: possible_cpus broken (again?) next-20130607 Dave Hansen @ 2013-06-11 22:05 ` Rafael J. Wysocki 2013-06-11 22:17 ` Dave Hansen 0 siblings, 1 reply; 12+ messages in thread From: Rafael J. Wysocki @ 2013-06-11 22:05 UTC (permalink / raw) To: Dave Hansen; +Cc: Toshi Kani, LKML On Tuesday, June 11, 2013 02:51:33 PM Dave Hansen wrote: > possible_cpus looks broken again. I'm booting with: > > maxcpus=10 possible_cpus=160 > > But I only get 0-9 in sysfs: > > > # ls /sys/devices/system/cpu/ > > cpu0 cpu2 cpu4 cpu6 cpu8 cpufreq kernel_max offline possible probe uevent > > cpu1 cpu3 cpu5 cpu7 cpu9 cpuidle modalias online present release Can you please test the acpi-hotplug branch of the linux-pm.git tree? Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: cpu hotplug: possible_cpus broken (again?) next-20130607 2013-06-11 22:05 ` Rafael J. Wysocki @ 2013-06-11 22:17 ` Dave Hansen 2013-06-11 22:34 ` Rafael J. Wysocki 0 siblings, 1 reply; 12+ messages in thread From: Dave Hansen @ 2013-06-11 22:17 UTC (permalink / raw) To: Rafael J. Wysocki; +Cc: Toshi Kani, LKML On 06/11/2013 03:05 PM, Rafael J. Wysocki wrote: > On Tuesday, June 11, 2013 02:51:33 PM Dave Hansen wrote: >> possible_cpus looks broken again. I'm booting with: >> >> maxcpus=10 possible_cpus=160 >> >> But I only get 0-9 in sysfs: >> >>> # ls /sys/devices/system/cpu/ >>> cpu0 cpu2 cpu4 cpu6 cpu8 cpufreq kernel_max offline possible probe uevent >>> cpu1 cpu3 cpu5 cpu7 cpu9 cpuidle modalias online present release > > Can you please test the acpi-hotplug branch of the linux-pm.git tree? That branch seems to work happily. ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: cpu hotplug: possible_cpus broken (again?) next-20130607 2013-06-11 22:17 ` Dave Hansen @ 2013-06-11 22:34 ` Rafael J. Wysocki 2013-06-11 22:32 ` Toshi Kani 0 siblings, 1 reply; 12+ messages in thread From: Rafael J. Wysocki @ 2013-06-11 22:34 UTC (permalink / raw) To: Dave Hansen; +Cc: Toshi Kani, LKML, Stephen Rothwell, Greg Kroah-Hartman On Tuesday, June 11, 2013 03:17:28 PM Dave Hansen wrote: > On 06/11/2013 03:05 PM, Rafael J. Wysocki wrote: > > On Tuesday, June 11, 2013 02:51:33 PM Dave Hansen wrote: > >> possible_cpus looks broken again. I'm booting with: > >> > >> maxcpus=10 possible_cpus=160 > >> > >> But I only get 0-9 in sysfs: > >> > >>> # ls /sys/devices/system/cpu/ > >>> cpu0 cpu2 cpu4 cpu6 cpu8 cpufreq kernel_max offline possible probe uevent > >>> cpu1 cpu3 cpu5 cpu7 cpu9 cpuidle modalias online present release > > > > Can you please test the acpi-hotplug branch of the linux-pm.git tree? > > That branch seems to work happily. In that case the problem may have been reintroduced by a merge conflict fix in linux-next. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: cpu hotplug: possible_cpus broken (again?) next-20130607 2013-06-11 22:34 ` Rafael J. Wysocki @ 2013-06-11 22:32 ` Toshi Kani 2013-06-12 12:03 ` Youquan Song 0 siblings, 1 reply; 12+ messages in thread From: Toshi Kani @ 2013-06-11 22:32 UTC (permalink / raw) To: Rafael J. Wysocki, youquan.song Cc: Dave Hansen, LKML, Stephen Rothwell, Greg Kroah-Hartman, akpm On Wed, 2013-06-12 at 00:34 +0200, Rafael J. Wysocki wrote: > On Tuesday, June 11, 2013 03:17:28 PM Dave Hansen wrote: > > On 06/11/2013 03:05 PM, Rafael J. Wysocki wrote: > > > On Tuesday, June 11, 2013 02:51:33 PM Dave Hansen wrote: > > >> possible_cpus looks broken again. I'm booting with: > > >> > > >> maxcpus=10 possible_cpus=160 > > >> > > >> But I only get 0-9 in sysfs: > > >> > > >>> # ls /sys/devices/system/cpu/ > > >>> cpu0 cpu2 cpu4 cpu6 cpu8 cpufreq kernel_max offline possible probe uevent > > >>> cpu1 cpu3 cpu5 cpu7 cpu9 cpuidle modalias online present release > > > > > > Can you please test the acpi-hotplug branch of the linux-pm.git tree? > > > > That branch seems to work happily. > > In that case the problem may have been reintroduced by a merge conflict fix in > linux-next. I believe the problem was introduced by the following change. From the description, though, this is exactly what this patch was trying to change... Adding Youguan to the list. commit 3e275a5ba367ab74b3a4e49114307baed989fcac Author: Youquan Song <youquan.song@intel.com> Date: Fri Jun 7 10:07:08 2013 +1000 drivers/base/cpu.c: fix maxcpus boot option Thanks, -Toshi ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: cpu hotplug: possible_cpus broken (again?) next-20130607 2013-06-11 22:32 ` Toshi Kani @ 2013-06-12 12:03 ` Youquan Song 2013-06-12 0:24 ` Dave Hansen 0 siblings, 1 reply; 12+ messages in thread From: Youquan Song @ 2013-06-12 12:03 UTC (permalink / raw) To: Toshi Kani Cc: Rafael J. Wysocki, youquan.song, Dave Hansen, LKML, Stephen Rothwell, Greg Kroah-Hartman, akpm, youquan.song On Tue, Jun 11, 2013 at 04:32:34PM -0600, Toshi Kani wrote: > On Wed, 2013-06-12 at 00:34 +0200, Rafael J. Wysocki wrote: > > On Tuesday, June 11, 2013 03:17:28 PM Dave Hansen wrote: > > > On 06/11/2013 03:05 PM, Rafael J. Wysocki wrote: > > > > On Tuesday, June 11, 2013 02:51:33 PM Dave Hansen wrote: > > > >> possible_cpus looks broken again. I'm booting with: > > > >> > > > >> maxcpus=10 possible_cpus=160 > > > >> > > > >> But I only get 0-9 in sysfs: > > > >> > > > >>> # ls /sys/devices/system/cpu/ > > > >>> cpu0 cpu2 cpu4 cpu6 cpu8 cpufreq kernel_max offline possible probe uevent > > > >>> cpu1 cpu3 cpu5 cpu7 cpu9 cpuidle modalias online present release > > > > > > > > Can you please test the acpi-hotplug branch of the linux-pm.git tree? > > > > > > That branch seems to work happily. > > > > In that case the problem may have been reintroduced by a merge conflict fix in > > linux-next. > > I believe the problem was introduced by the following change. From the > description, though, this is exactly what this patch was trying to > change... Adding Youguan to the list. > > commit 3e275a5ba367ab74b3a4e49114307baed989fcac > Author: Youquan Song <youquan.song@intel.com> > Date: Fri Jun 7 10:07:08 2013 +1000 > > drivers/base/cpu.c: fix maxcpus boot option > Hi Toshi, Thanks Thoshi for the information. please try the below patch to fix the issue by moving the code to store_online. diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index 3d48fc8..2378f42 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -60,6 +60,13 @@ static ssize_t __ref store_online(struct device *dev, kobject_uevent(&dev->kobj, KOBJ_OFFLINE); break; case '1': +#ifdef CONFIG_SMP + /* return when cpu number greater than maximum number of CPUs */ + if (setup_max_cpus <= num_online_cpus() + 1) { + cpu_hotplug_driver_unlock(); + return -EINVAL; + } +#endif from_nid = cpu_to_node(cpuid); ret = cpu_up(cpuid); Thanks -Youquan ^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: cpu hotplug: possible_cpus broken (again?) next-20130607 2013-06-12 12:03 ` Youquan Song @ 2013-06-12 0:24 ` Dave Hansen 2013-06-12 12:32 ` Youquan Song 0 siblings, 1 reply; 12+ messages in thread From: Dave Hansen @ 2013-06-12 0:24 UTC (permalink / raw) To: Youquan Song Cc: Toshi Kani, Rafael J. Wysocki, youquan.song, LKML, Stephen Rothwell, Greg Kroah-Hartman, akpm On 06/12/2013 05:03 AM, Youquan Song wrote: > +#ifdef CONFIG_SMP > + /* return when cpu number greater than maximum number of > CPUs */ > + if (setup_max_cpus <= num_online_cpus() + 1) { > + cpu_hotplug_driver_unlock(); > + return -EINVAL; > + } > +#endif > from_nid = cpu_to_node(cpuid); > ret = cpu_up(cpuid); Your patch is line-wrapped. Also, the #ifdef is unnecessary. If CONFIG_SMP is off: static const unsigned int setup_max_cpus = NR_CPUS; #define num_online_cpus() 1U The compiler will take care of optimizing out the the if() without the explicit #ifdef. Also, the +1 looks goofy to me. Doesn't this do the same thing (and isn't it much easier to read)? if (num_online_cpus() >= setup_max_cpus) ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: cpu hotplug: possible_cpus broken (again?) next-20130607 2013-06-12 0:24 ` Dave Hansen @ 2013-06-12 12:32 ` Youquan Song 2013-06-12 4:07 ` Yinghai Lu 0 siblings, 1 reply; 12+ messages in thread From: Youquan Song @ 2013-06-12 12:32 UTC (permalink / raw) To: Dave Hansen Cc: Youquan Song, Toshi Kani, Rafael J. Wysocki, youquan.song, LKML, Stephen Rothwell, Greg Kroah-Hartman, akpm > On 06/12/2013 05:03 AM, Youquan Song wrote: > > +#ifdef CONFIG_SMP > > + /* return when cpu number greater than maximum number of > > CPUs */ > > + if (setup_max_cpus <= num_online_cpus() + 1) { > > + cpu_hotplug_driver_unlock(); > > + return -EINVAL; > > + } > > +#endif > > from_nid = cpu_to_node(cpuid); > > ret = cpu_up(cpuid); > > Your patch is line-wrapped. > > Also, the #ifdef is unnecessary. If CONFIG_SMP is off: > > static const unsigned int setup_max_cpus = NR_CPUS; > #define num_online_cpus() 1U > > The compiler will take care of optimizing out the the if() without the > explicit #ifdef. > > Also, the +1 looks goofy to me. Doesn't this do the same thing (and > isn't it much easier to read)? > > if (num_online_cpus() >= setup_max_cpus) > Thanks. Here is a formal patch for it. please review and try. Subject: [PATCH] core: Fix maxcpus boot option broken maxcpus boot option to limit maximum number of CPUs on system, but this option is broken at recent kernel. Though we use maxcpus to limit CPUs number, but current kernel will register all of present CPUs in sysfs. udev will enumerate all registered cpu at sysfs, and it will bring up the CPU if the CPU is offline. So the maxcpus option is broken. This patch will limit the online cpus number not over limitation of maxcpus option. So it will keep the maxcpus limitation when udev enumeration or other intention of bring up CPUs over the limitation by method like echo 1 > /sys/devices/system/cpu/online Signed-off-by: Youquan Song <youquan.song@intel.com> --- diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index 3d48fc8..e32fffa 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -60,6 +60,13 @@ static ssize_t __ref store_online(struct device *dev, kobject_uevent(&dev->kobj, KOBJ_OFFLINE); break; case '1': + /* Return when online cpu number equal or greater than + * maximum number of CPUs */ + if (num_online_cpus() >= setup_max_cpus) { + cpu_hotplug_driver_unlock(); + return -EINVAL; + } + from_nid = cpu_to_node(cpuid); ret = cpu_up(cpuid); ^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: cpu hotplug: possible_cpus broken (again?) next-20130607 2013-06-12 12:32 ` Youquan Song @ 2013-06-12 4:07 ` Yinghai Lu 2013-06-12 11:02 ` Rafael J. Wysocki 0 siblings, 1 reply; 12+ messages in thread From: Yinghai Lu @ 2013-06-12 4:07 UTC (permalink / raw) To: Youquan Song, Greg Kroah-Hartman, Andrew Morton Cc: Dave Hansen, Toshi Kani, Rafael J. Wysocki, Youquan Song, LKML, Stephen Rothwell On Wed, Jun 12, 2013 at 5:32 AM, Youquan Song <youquan.song@linux.intel.com> wrote: >> On 06/12/2013 05:03 AM, Youquan Song wrote: >> > +#ifdef CONFIG_SMP >> > + /* return when cpu number greater than maximum number of >> > CPUs */ >> > + if (setup_max_cpus <= num_online_cpus() + 1) { >> > + cpu_hotplug_driver_unlock(); >> > + return -EINVAL; >> > + } >> > +#endif >> > from_nid = cpu_to_node(cpuid); >> > ret = cpu_up(cpuid); >> >> Your patch is line-wrapped. >> >> Also, the #ifdef is unnecessary. If CONFIG_SMP is off: >> >> static const unsigned int setup_max_cpus = NR_CPUS; >> #define num_online_cpus() 1U >> >> The compiler will take care of optimizing out the the if() without the >> explicit #ifdef. >> >> Also, the +1 looks goofy to me. Doesn't this do the same thing (and >> isn't it much easier to read)? >> >> if (num_online_cpus() >= setup_max_cpus) >> > > Thanks. Here is a formal patch for it. please review and try. > > Subject: [PATCH] core: Fix maxcpus boot option broken > > maxcpus boot option to limit maximum number of CPUs on system, but this option > is broken at recent kernel. Though we use maxcpus to limit CPUs number, but > current kernel will register all of present CPUs in sysfs. > udev will enumerate all registered cpu at sysfs, and it will bring up the CPU > if the CPU is offline. So the maxcpus option is broken. > > This patch will limit the online cpus number not over limitation of maxcpus > option. So it will keep the maxcpus limitation when udev enumeration > or other intention of bring up CPUs over the limitation by method like > echo 1 > /sys/devices/system/cpu/online Interesting, you are changing long standing meaning of maxcpus= We always use maxcpus=1 to have one cpu up, and later in user space to online other cpus like echo 1 > /sys/devices/system/cpuX/online. aka maxcpus= is a soft limit or initial online nr. we already have nr_cpus= for hard limit. So need to drop commit 3e275a5ba367ab74b3a4e49114307baed989fcac Author: Youquan Song <youquan.song@intel.com> Date: Fri Jun 7 10:07:08 2013 +1000 drivers/base/cpu.c: fix maxcpus boot option Greg, Can you drop that 3e275a5ba36 from your drivers/core tree ? Thanks Yinghai ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: cpu hotplug: possible_cpus broken (again?) next-20130607 2013-06-12 4:07 ` Yinghai Lu @ 2013-06-12 11:02 ` Rafael J. Wysocki 2013-06-13 1:36 ` Youquan Song 0 siblings, 1 reply; 12+ messages in thread From: Rafael J. Wysocki @ 2013-06-12 11:02 UTC (permalink / raw) To: Yinghai Lu Cc: Youquan Song, Greg Kroah-Hartman, Andrew Morton, Dave Hansen, Toshi Kani, Youquan Song, LKML, Stephen Rothwell On Tuesday, June 11, 2013 09:07:37 PM Yinghai Lu wrote: > On Wed, Jun 12, 2013 at 5:32 AM, Youquan Song > <youquan.song@linux.intel.com> wrote: > >> On 06/12/2013 05:03 AM, Youquan Song wrote: > >> > +#ifdef CONFIG_SMP > >> > + /* return when cpu number greater than maximum number of > >> > CPUs */ > >> > + if (setup_max_cpus <= num_online_cpus() + 1) { > >> > + cpu_hotplug_driver_unlock(); > >> > + return -EINVAL; > >> > + } > >> > +#endif > >> > from_nid = cpu_to_node(cpuid); > >> > ret = cpu_up(cpuid); > >> > >> Your patch is line-wrapped. > >> > >> Also, the #ifdef is unnecessary. If CONFIG_SMP is off: > >> > >> static const unsigned int setup_max_cpus = NR_CPUS; > >> #define num_online_cpus() 1U > >> > >> The compiler will take care of optimizing out the the if() without the > >> explicit #ifdef. > >> > >> Also, the +1 looks goofy to me. Doesn't this do the same thing (and > >> isn't it much easier to read)? > >> > >> if (num_online_cpus() >= setup_max_cpus) > >> > > > > Thanks. Here is a formal patch for it. please review and try. > > > > Subject: [PATCH] core: Fix maxcpus boot option broken > > > > maxcpus boot option to limit maximum number of CPUs on system, but this option > > is broken at recent kernel. Though we use maxcpus to limit CPUs number, but > > current kernel will register all of present CPUs in sysfs. > > udev will enumerate all registered cpu at sysfs, and it will bring up the CPU > > if the CPU is offline. So the maxcpus option is broken. > > > > This patch will limit the online cpus number not over limitation of maxcpus > > option. So it will keep the maxcpus limitation when udev enumeration > > or other intention of bring up CPUs over the limitation by method like > > echo 1 > /sys/devices/system/cpu/online > > Interesting, you are changing long standing meaning of maxcpus= > > We always use maxcpus=1 to have one cpu up, and later in user space > to online other cpus like > echo 1 > /sys/devices/system/cpuX/online. > > aka maxcpus= is a soft limit or initial online nr. > > we already have nr_cpus= for hard limit. > > So need to drop > commit 3e275a5ba367ab74b3a4e49114307baed989fcac > Author: Youquan Song <youquan.song@intel.com> > Date: Fri Jun 7 10:07:08 2013 +1000 > > drivers/base/cpu.c: fix maxcpus boot option Agreed. Thanks, Rafael > Greg, > Can you drop that 3e275a5ba36 from your drivers/core tree ? > > Thanks > > Yinghai -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: cpu hotplug: possible_cpus broken (again?) next-20130607 2013-06-12 11:02 ` Rafael J. Wysocki @ 2013-06-13 1:36 ` Youquan Song 2013-06-13 15:36 ` Toshi Kani 0 siblings, 1 reply; 12+ messages in thread From: Youquan Song @ 2013-06-13 1:36 UTC (permalink / raw) To: Rafael J. Wysocki Cc: Yinghai Lu, Youquan Song, Greg Kroah-Hartman, Andrew Morton, Dave Hansen, Toshi Kani, Youquan Song, LKML, Stephen Rothwell > > Interesting, you are changing long standing meaning of maxcpus= > > > > We always use maxcpus=1 to have one cpu up, and later in user space > > to online other cpus like > > echo 1 > /sys/devices/system/cpuX/online. > > > > aka maxcpus= is a soft limit or initial online nr. > > > > we already have nr_cpus= for hard limit. > > > > So need to drop > > commit 3e275a5ba367ab74b3a4e49114307baed989fcac > > Author: Youquan Song <youquan.song@intel.com> > > Date: Fri Jun 7 10:07:08 2013 +1000 > > > > drivers/base/cpu.c: fix maxcpus boot option > > Agreed. Yes. I also agree to drop it and the fix need more consideration. I try use maxcpus to limit cpu number to debug a well known applition because it fail to run when cpu number is larger to > 69. When I use maxcpus at to limit the boot CPUs number, but udev will enable all of the CPUs at 3.10 kernel automatically. I also try maxcpus at 3.0 kernel, it does not show the maxcpus issue. I have digged out recently, it is the commit at 3.2 kernel 8a25a2fd126c621f44f3aeaef80d51f00fc11639 "cpu: convert 'cpu' and 'machinecheck' sysdev_class to a regular subsystem" result in udev automatically enable all of CPUs though maxcpus has been provided. So the next, I need look at udev try to enable all of CPUs though maxcpus provided. Possibly, it can also fix it in udev daemon. Secondly, I think that the maxcpus= option description is too confused in Documentation/kernel-parameters.txt. The maxcpus and nr_cpus option need switch their name. Currently: maxcpus= [SMP] Maximum number of processors that an SMP kernel should make use of. maxcpus=n : n >= 0 limits the kernel to using 'n' processors. n=0 is a special case, it is equivalent to "nosmp", which also disables the IO APIC. How about change to maxcpus= [SMP] Maximum number of processors that an SMP kernel bring up during booting. maxcpus=n : n >= 0 limits the kernel to using 'n' processors. n=0 is a special case, it is equivalent to "nosmp", which also disables the IO APIC. Thanks -Youquan ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: cpu hotplug: possible_cpus broken (again?) next-20130607 2013-06-13 1:36 ` Youquan Song @ 2013-06-13 15:36 ` Toshi Kani 0 siblings, 0 replies; 12+ messages in thread From: Toshi Kani @ 2013-06-13 15:36 UTC (permalink / raw) To: Youquan Song Cc: Rafael J. Wysocki, Yinghai Lu, Greg Kroah-Hartman, Andrew Morton, Dave Hansen, Youquan Song, LKML, Stephen Rothwell On Wed, 2013-06-12 at 21:36 -0400, Youquan Song wrote: > > > Interesting, you are changing long standing meaning of maxcpus= > > > > > > We always use maxcpus=1 to have one cpu up, and later in user space > > > to online other cpus like > > > echo 1 > /sys/devices/system/cpuX/online. > > > > > > aka maxcpus= is a soft limit or initial online nr. > > > > > > we already have nr_cpus= for hard limit. > > > > > > So need to drop > > > commit 3e275a5ba367ab74b3a4e49114307baed989fcac > > > Author: Youquan Song <youquan.song@intel.com> > > > Date: Fri Jun 7 10:07:08 2013 +1000 > > > > > > drivers/base/cpu.c: fix maxcpus boot option > > > > Agreed. > > Yes. I also agree to drop it and the fix need more consideration. Agreed. > I try use maxcpus to limit cpu number to debug a well known applition > because it fail to run when cpu number is larger to > 69. > When I use maxcpus at to limit the boot CPUs number, but udev will > enable all of the CPUs at 3.10 kernel automatically. > I also try maxcpus at 3.0 kernel, it does not show the maxcpus issue. I tested Linus's 3.10-rc5 kernel on Fedora 18, but I did not see such behavior. Could this be related with your environment? > I have digged out recently, it is the commit at 3.2 kernel > 8a25a2fd126c621f44f3aeaef80d51f00fc11639 "cpu: convert 'cpu' and > 'machinecheck' sysdev_class to a regular subsystem" result in udev > automatically enable all of CPUs though maxcpus has been provided. > > So the next, I need look at udev try to enable all of CPUs though > maxcpus provided. Possibly, it can also fix it in udev daemon. > > Secondly, I think that the maxcpus= option description is too confused in > Documentation/kernel-parameters.txt. The maxcpus and nr_cpus option need > switch their name. I am fine with the clarification. > Currently: > > maxcpus= [SMP] Maximum number of processors that an SMP kernel > should make use of. maxcpus=n : n >= 0 limits the > kernel to using 'n' processors. n=0 is a special case, > it is equivalent to "nosmp", which also disables > the IO APIC. > > How about change to > > maxcpus= [SMP] Maximum number of processors that an SMP kernel > bring up during booting. maxcpus=n : n >= 0 limits the bring -> brings > kernel to using 'n' processors. n=0 is a special case, > it is equivalent to "nosmp", which also disables > the IO APIC. Thanks, -Toshi ^ permalink raw reply [flat|nested] 12+ messages in thread
end of thread, other threads:[~2013-06-13 15:36 UTC | newest] Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2013-06-11 21:51 cpu hotplug: possible_cpus broken (again?) next-20130607 Dave Hansen 2013-06-11 22:05 ` Rafael J. Wysocki 2013-06-11 22:17 ` Dave Hansen 2013-06-11 22:34 ` Rafael J. Wysocki 2013-06-11 22:32 ` Toshi Kani 2013-06-12 12:03 ` Youquan Song 2013-06-12 0:24 ` Dave Hansen 2013-06-12 12:32 ` Youquan Song 2013-06-12 4:07 ` Yinghai Lu 2013-06-12 11:02 ` Rafael J. Wysocki 2013-06-13 1:36 ` Youquan Song 2013-06-13 15:36 ` Toshi Kani
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