* [PATCH v3 1/2] Documentation: kdump: remind user of nr_cpus
@ 2016-08-03 0:59 Zhou Wenjian
2016-08-03 0:59 ` [PATCH v3 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel Zhou Wenjian
` (2 more replies)
0 siblings, 3 replies; 8+ messages in thread
From: Zhou Wenjian @ 2016-08-03 0:59 UTC (permalink / raw)
To: linux-kernel; +Cc: kexec, bhe, dyoung, d.hatayama
v2->v3: add description of nr_cpus.
v1->v2: change nr_cpus to maxcpus
nr_cpus can help to save memory. So we should remind user of it.
Signed-off-by: Zhou Wenjian <zhouwj-fnst@cn.fujitsu.com>
---
Documentation/kdump/kdump.txt | 2 ++
1 file changed, 2 insertions(+)
diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index 88ff63d..4aa194e 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -393,6 +393,8 @@ Notes on loading the dump-capture kernel:
* We generally don' have to bring up a SMP kernel just to capture the
dump. Hence generally it is useful either to build a UP dump-capture
kernel or specify maxcpus=1 option while loading dump-capture kernel.
+ Note, though maxcpus always works, we should replace it by nr_cpus to
+ save memory if supported by the current ARCH, such as x86.
* For s390x there are two kdump modes: If a ELF header is specified with
the elfcorehdr= kernel parameter, it is used by the kdump kernel as it
--
1.8.3.1
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH v3 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel 2016-08-03 0:59 [PATCH v3 1/2] Documentation: kdump: remind user of nr_cpus Zhou Wenjian @ 2016-08-03 0:59 ` Zhou Wenjian 2016-08-03 1:58 ` Baoquan He 2016-08-03 1:23 ` [PATCH v3 1/2] Documentation: kdump: remind user of nr_cpus Baoquan He 2016-08-08 2:14 ` Dave Young 2 siblings, 1 reply; 8+ messages in thread From: Zhou Wenjian @ 2016-08-03 0:59 UTC (permalink / raw) To: linux-kernel; +Cc: kexec, bhe, dyoung, d.hatayama SMP dump-capture kernel is useful to improve the performance of kdump in some cases. So add the description of bringing up SMP dump-capture kernel. Signed-off-by: Zhou Wenjian <zhouwj-fnst@cn.fujitsu.com> --- Documentation/kdump/kdump.txt | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt index 4aa194e..948b42d 100644 --- a/Documentation/kdump/kdump.txt +++ b/Documentation/kdump/kdump.txt @@ -396,6 +396,13 @@ Notes on loading the dump-capture kernel: Note, though maxcpus always works, we should replace it by nr_cpus to save memory if supported by the current ARCH, such as x86. +* We should bring up a SMP dump-capture kernel if we intend to use + multi-threads programs with it, such as parallel dump feature of + makedumpfile. Otherwise, the multi-threads program may have a great + performance degradation. To bring up a SMP dump-capture kernel, we + should specify maxcpus\nr_cpus and disable_cpu_apic=[X] options while + loading it. + * For s390x there are two kdump modes: If a ELF header is specified with the elfcorehdr= kernel parameter, it is used by the kdump kernel as it is done on all other architectures. If no elfcorehdr= kernel parameter is -- 1.8.3.1 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH v3 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel 2016-08-03 0:59 ` [PATCH v3 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel Zhou Wenjian @ 2016-08-03 1:58 ` Baoquan He 2016-08-03 2:05 ` "Zhou, Wenjian/周文剑" 0 siblings, 1 reply; 8+ messages in thread From: Baoquan He @ 2016-08-03 1:58 UTC (permalink / raw) To: Zhou Wenjian; +Cc: linux-kernel, dyoung, d.hatayama, kexec On 08/03/16 at 08:59am, Zhou Wenjian wrote: > SMP dump-capture kernel is useful to improve the performance of kdump in > some cases. So add the description of bringing up SMP dump-capture kernel. > > Signed-off-by: Zhou Wenjian <zhouwj-fnst@cn.fujitsu.com> > --- > Documentation/kdump/kdump.txt | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt > index 4aa194e..948b42d 100644 > --- a/Documentation/kdump/kdump.txt > +++ b/Documentation/kdump/kdump.txt > @@ -396,6 +396,13 @@ Notes on loading the dump-capture kernel: > Note, though maxcpus always works, we should replace it by nr_cpus to > save memory if supported by the current ARCH, such as x86. > > +* We should bring up a SMP dump-capture kernel if we intend to use Well, here about SMP dump-capture kernel do you mean kdump kernel with multi-cpu? If I understand it correctly, it's still SMP kdump kernel though nr_cpus=1 is specified. > + multi-threads programs with it, such as parallel dump feature of > + makedumpfile. Otherwise, the multi-threads program may have a great > + performance degradation. To bring up a SMP dump-capture kernel, we > + should specify maxcpus\nr_cpus and disable_cpu_apic=[X] options while > + loading it. > + > * For s390x there are two kdump modes: If a ELF header is specified with > the elfcorehdr= kernel parameter, it is used by the kdump kernel as it > is done on all other architectures. If no elfcorehdr= kernel parameter is > -- > 1.8.3.1 > > > > > _______________________________________________ > kexec mailing list > kexec@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v3 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel 2016-08-03 1:58 ` Baoquan He @ 2016-08-03 2:05 ` "Zhou, Wenjian/周文剑" 2016-08-03 2:18 ` Baoquan He 0 siblings, 1 reply; 8+ messages in thread From: "Zhou, Wenjian/周文剑" @ 2016-08-03 2:05 UTC (permalink / raw) To: Baoquan He; +Cc: linux-kernel, dyoung, d.hatayama, kexec On 08/03/2016 09:58 AM, Baoquan He wrote: > On 08/03/16 at 08:59am, Zhou Wenjian wrote: >> SMP dump-capture kernel is useful to improve the performance of kdump in >> some cases. So add the description of bringing up SMP dump-capture kernel. >> >> Signed-off-by: Zhou Wenjian <zhouwj-fnst@cn.fujitsu.com> >> --- >> Documentation/kdump/kdump.txt | 7 +++++++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt >> index 4aa194e..948b42d 100644 >> --- a/Documentation/kdump/kdump.txt >> +++ b/Documentation/kdump/kdump.txt >> @@ -396,6 +396,13 @@ Notes on loading the dump-capture kernel: >> Note, though maxcpus always works, we should replace it by nr_cpus to >> save memory if supported by the current ARCH, such as x86. >> >> +* We should bring up a SMP dump-capture kernel if we intend to use > > Well, here about SMP dump-capture kernel do you mean kdump kernel with > multi-cpu? If I understand it correctly, it's still SMP kdump kernel > though nr_cpus=1 is specified. > Actually, I haven't know the detail about it. I wrote the sentence almost based on the original description: * We generally don' have to bring up a SMP kernel just to capture the dump. Hence generally it is useful either to build a UP dump-capture kernel or specify maxcpus=1 option while loading dump-capture kernel. >> + multi-threads programs with it, such as parallel dump feature of >> + makedumpfile. Otherwise, the multi-threads program may have a great >> + performance degradation. To bring up a SMP dump-capture kernel, we >> + should specify maxcpus\nr_cpus and disable_cpu_apic=[X] options while >> + loading it. >> + >> * For s390x there are two kdump modes: If a ELF header is specified with >> the elfcorehdr= kernel parameter, it is used by the kdump kernel as it >> is done on all other architectures. If no elfcorehdr= kernel parameter is >> -- >> 1.8.3.1 >> >> >> >> >> _______________________________________________ >> kexec mailing list >> kexec@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/kexec > > -- Thanks Zhou ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v3 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel 2016-08-03 2:05 ` "Zhou, Wenjian/周文剑" @ 2016-08-03 2:18 ` Baoquan He 2016-08-03 2:19 ` "Zhou, Wenjian/周文剑" 0 siblings, 1 reply; 8+ messages in thread From: Baoquan He @ 2016-08-03 2:18 UTC (permalink / raw) To: "Zhou, Wenjian/周文剑" Cc: linux-kernel, dyoung, d.hatayama, kexec On 08/03/16 at 10:05am, "Zhou, Wenjian/周文剑" wrote: > On 08/03/2016 09:58 AM, Baoquan He wrote: > >On 08/03/16 at 08:59am, Zhou Wenjian wrote: > >>SMP dump-capture kernel is useful to improve the performance of kdump in > >>some cases. So add the description of bringing up SMP dump-capture kernel. > >> > >>Signed-off-by: Zhou Wenjian <zhouwj-fnst@cn.fujitsu.com> > >>--- > >> Documentation/kdump/kdump.txt | 7 +++++++ > >> 1 file changed, 7 insertions(+) > >> > >>diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt > >>index 4aa194e..948b42d 100644 > >>--- a/Documentation/kdump/kdump.txt > >>+++ b/Documentation/kdump/kdump.txt > >>@@ -396,6 +396,13 @@ Notes on loading the dump-capture kernel: > >> Note, though maxcpus always works, we should replace it by nr_cpus to > >> save memory if supported by the current ARCH, such as x86. > >> > >>+* We should bring up a SMP dump-capture kernel if we intend to use > > > >Well, here about SMP dump-capture kernel do you mean kdump kernel with > >multi-cpu? If I understand it correctly, it's still SMP kdump kernel > >though nr_cpus=1 is specified. > > > > Actually, I haven't know the detail about it. I wrote the sentence almost > based on the original description: > > * We generally don' have to bring up a SMP kernel just to capture the > dump. Hence generally it is useful either to build a UP dump-capture > kernel or specify maxcpus=1 option while loading dump-capture kernel. This is right. Here it means either you build a UP kernel used for kdump kernel because kdump kernel doesn't have to be the same as the 1st kernel, or you use smp kernel with maxcpus=1 specified. So if you want to say kdump kernel with multi-cpu need be brought up to improve the performance of parallel dumping, you need point it out clearly. > > >>+ multi-threads programs with it, such as parallel dump feature of > >>+ makedumpfile. Otherwise, the multi-threads program may have a great > >>+ performance degradation. To bring up a SMP dump-capture kernel, we > >>+ should specify maxcpus\nr_cpus and disable_cpu_apic=[X] options while > >>+ loading it. > >>+ > >> * For s390x there are two kdump modes: If a ELF header is specified with > >> the elfcorehdr= kernel parameter, it is used by the kdump kernel as it > >> is done on all other architectures. If no elfcorehdr= kernel parameter is > >>-- > >>1.8.3.1 > >> > >> > >> > >> > >>_______________________________________________ > >>kexec mailing list > >>kexec@lists.infradead.org > >>http://lists.infradead.org/mailman/listinfo/kexec > > > > > > > -- > Thanks > Zhou > > ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v3 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel 2016-08-03 2:18 ` Baoquan He @ 2016-08-03 2:19 ` "Zhou, Wenjian/周文剑" 0 siblings, 0 replies; 8+ messages in thread From: "Zhou, Wenjian/周文剑" @ 2016-08-03 2:19 UTC (permalink / raw) To: Baoquan He; +Cc: linux-kernel, dyoung, d.hatayama, kexec On 08/03/2016 10:18 AM, Baoquan He wrote: > On 08/03/16 at 10:05am, "Zhou, Wenjian/周文剑" wrote: >> On 08/03/2016 09:58 AM, Baoquan He wrote: >>> On 08/03/16 at 08:59am, Zhou Wenjian wrote: >>>> SMP dump-capture kernel is useful to improve the performance of kdump in >>>> some cases. So add the description of bringing up SMP dump-capture kernel. >>>> >>>> Signed-off-by: Zhou Wenjian <zhouwj-fnst@cn.fujitsu.com> >>>> --- >>>> Documentation/kdump/kdump.txt | 7 +++++++ >>>> 1 file changed, 7 insertions(+) >>>> >>>> diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt >>>> index 4aa194e..948b42d 100644 >>>> --- a/Documentation/kdump/kdump.txt >>>> +++ b/Documentation/kdump/kdump.txt >>>> @@ -396,6 +396,13 @@ Notes on loading the dump-capture kernel: >>>> Note, though maxcpus always works, we should replace it by nr_cpus to >>>> save memory if supported by the current ARCH, such as x86. >>>> >>>> +* We should bring up a SMP dump-capture kernel if we intend to use >>> >>> Well, here about SMP dump-capture kernel do you mean kdump kernel with >>> multi-cpu? If I understand it correctly, it's still SMP kdump kernel >>> though nr_cpus=1 is specified. >>> >> >> Actually, I haven't know the detail about it. I wrote the sentence almost >> based on the original description: >> >> * We generally don' have to bring up a SMP kernel just to capture the >> dump. Hence generally it is useful either to build a UP dump-capture >> kernel or specify maxcpus=1 option while loading dump-capture kernel. > > This is right. Here it means either you build a UP kernel used for kdump > kernel because kdump kernel doesn't have to be the same as the 1st > kernel, or you use smp kernel with maxcpus=1 specified. So if you want > to say kdump kernel with multi-cpu need be brought up to improve the > performance of parallel dumping, you need point it out clearly. > I see. I will update the patch. >> >>>> + multi-threads programs with it, such as parallel dump feature of >>>> + makedumpfile. Otherwise, the multi-threads program may have a great >>>> + performance degradation. To bring up a SMP dump-capture kernel, we >>>> + should specify maxcpus\nr_cpus and disable_cpu_apic=[X] options while >>>> + loading it. >>>> + >>>> * For s390x there are two kdump modes: If a ELF header is specified with >>>> the elfcorehdr= kernel parameter, it is used by the kdump kernel as it >>>> is done on all other architectures. If no elfcorehdr= kernel parameter is >>>> -- >>>> 1.8.3.1 >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> kexec mailing list >>>> kexec@lists.infradead.org >>>> http://lists.infradead.org/mailman/listinfo/kexec >>> >>> >> >> >> -- >> Thanks >> Zhou >> >> > > -- Thanks Zhou ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v3 1/2] Documentation: kdump: remind user of nr_cpus 2016-08-03 0:59 [PATCH v3 1/2] Documentation: kdump: remind user of nr_cpus Zhou Wenjian 2016-08-03 0:59 ` [PATCH v3 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel Zhou Wenjian @ 2016-08-03 1:23 ` Baoquan He 2016-08-08 2:14 ` Dave Young 2 siblings, 0 replies; 8+ messages in thread From: Baoquan He @ 2016-08-03 1:23 UTC (permalink / raw) To: Zhou Wenjian, akpm; +Cc: linux-kernel, kexec, dyoung, d.hatayama On 08/03/16 at 08:59am, Zhou Wenjian wrote: > v2->v3: add description of nr_cpus. > v1->v2: change nr_cpus to maxcpus > > nr_cpus can help to save memory. So we should remind user of it. > > Signed-off-by: Zhou Wenjian <zhouwj-fnst@cn.fujitsu.com> > --- > Documentation/kdump/kdump.txt | 2 ++ > 1 file changed, 2 insertions(+) Looks good to me! Thanks, Wenjian. Ack this series Acked-by: Baoquan He <bhe@redhat.com> Hi Andrew, Could you please help merge this patchset? Thanks Baoquan > > diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt > index 88ff63d..4aa194e 100644 > --- a/Documentation/kdump/kdump.txt > +++ b/Documentation/kdump/kdump.txt > @@ -393,6 +393,8 @@ Notes on loading the dump-capture kernel: > * We generally don' have to bring up a SMP kernel just to capture the > dump. Hence generally it is useful either to build a UP dump-capture > kernel or specify maxcpus=1 option while loading dump-capture kernel. > + Note, though maxcpus always works, we should replace it by nr_cpus to > + save memory if supported by the current ARCH, such as x86. > > * For s390x there are two kdump modes: If a ELF header is specified with > the elfcorehdr= kernel parameter, it is used by the kdump kernel as it > -- > 1.8.3.1 > > > ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v3 1/2] Documentation: kdump: remind user of nr_cpus 2016-08-03 0:59 [PATCH v3 1/2] Documentation: kdump: remind user of nr_cpus Zhou Wenjian 2016-08-03 0:59 ` [PATCH v3 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel Zhou Wenjian 2016-08-03 1:23 ` [PATCH v3 1/2] Documentation: kdump: remind user of nr_cpus Baoquan He @ 2016-08-08 2:14 ` Dave Young 2 siblings, 0 replies; 8+ messages in thread From: Dave Young @ 2016-08-08 2:14 UTC (permalink / raw) To: Zhou Wenjian; +Cc: linux-kernel, d.hatayama, kexec, bhe On 08/03/16 at 08:59am, Zhou Wenjian wrote: > v2->v3: add description of nr_cpus. > v1->v2: change nr_cpus to maxcpus > > nr_cpus can help to save memory. So we should remind user of it. > > Signed-off-by: Zhou Wenjian <zhouwj-fnst@cn.fujitsu.com> > --- > Documentation/kdump/kdump.txt | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt > index 88ff63d..4aa194e 100644 > --- a/Documentation/kdump/kdump.txt > +++ b/Documentation/kdump/kdump.txt > @@ -393,6 +393,8 @@ Notes on loading the dump-capture kernel: > * We generally don' have to bring up a SMP kernel just to capture the > dump. Hence generally it is useful either to build a UP dump-capture > kernel or specify maxcpus=1 option while loading dump-capture kernel. > + Note, though maxcpus always works, we should replace it by nr_cpus to > + save memory if supported by the current ARCH, such as x86. Can you replace "we" with "you" in both these patches? Thanks Dave ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2016-08-08 2:15 UTC | newest] Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2016-08-03 0:59 [PATCH v3 1/2] Documentation: kdump: remind user of nr_cpus Zhou Wenjian 2016-08-03 0:59 ` [PATCH v3 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel Zhou Wenjian 2016-08-03 1:58 ` Baoquan He 2016-08-03 2:05 ` "Zhou, Wenjian/周文剑" 2016-08-03 2:18 ` Baoquan He 2016-08-03 2:19 ` "Zhou, Wenjian/周文剑" 2016-08-03 1:23 ` [PATCH v3 1/2] Documentation: kdump: remind user of nr_cpus Baoquan He 2016-08-08 2:14 ` Dave Young
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