* [PATCH 1/2] Documentation: kdump: update maxcpus to nr_cpus
@ 2016-07-29 3:23 Zhou Wenjian
2016-07-29 3:23 ` [PATCH 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel Zhou Wenjian
2016-07-30 2:19 ` [PATCH 1/2] Documentation: kdump: update maxcpus to nr_cpus Baoquan He
0 siblings, 2 replies; 3+ messages in thread
From: Zhou Wenjian @ 2016-07-29 3:23 UTC (permalink / raw)
To: linux-kernel; +Cc: kexec, bhe, dyoung, d.hatayama
Parameter nr_cpus is used to bring up a SMP dump-capture kernel,
instead of the old parameter maxcpus. This commit update it in
Documentation/kdump/kdump.txt.
Signed-off-by: Zhou Wenjian <zhouwj-fnst@cn.fujitsu.com>
---
Documentation/kdump/kdump.txt | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index 88ff63d..9a77247 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -392,7 +392,7 @@ 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.
+ kernel or specify nr_cpus=1 option while loading dump-capture kernel.
* 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] 3+ messages in thread
* [PATCH 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel
2016-07-29 3:23 [PATCH 1/2] Documentation: kdump: update maxcpus to nr_cpus Zhou Wenjian
@ 2016-07-29 3:23 ` Zhou Wenjian
2016-07-30 2:19 ` [PATCH 1/2] Documentation: kdump: update maxcpus to nr_cpus Baoquan He
1 sibling, 0 replies; 3+ messages in thread
From: Zhou Wenjian @ 2016-07-29 3:23 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 | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index 9a77247..155a63c 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -394,6 +394,12 @@ Notes on loading the dump-capture kernel:
dump. Hence generally it is useful either to build a UP dump-capture
kernel or specify nr_cpus=1 option while loading dump-capture kernel.
+* 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 nr_cpus=[X] and
+ disable_cpu_apic=[Y] 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] 3+ messages in thread
* Re: [PATCH 1/2] Documentation: kdump: update maxcpus to nr_cpus
2016-07-29 3:23 [PATCH 1/2] Documentation: kdump: update maxcpus to nr_cpus Zhou Wenjian
2016-07-29 3:23 ` [PATCH 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel Zhou Wenjian
@ 2016-07-30 2:19 ` Baoquan He
1 sibling, 0 replies; 3+ messages in thread
From: Baoquan He @ 2016-07-30 2:19 UTC (permalink / raw)
To: Zhou Wenjian; +Cc: linux-kernel, kexec, dyoung, d.hatayama
On 07/29/16 at 11:23am, Zhou Wenjian wrote:
> Parameter nr_cpus is used to bring up a SMP dump-capture kernel,
> instead of the old parameter maxcpus. This commit update it in
> Documentation/kdump/kdump.txt.
>
> Signed-off-by: Zhou Wenjian <zhouwj-fnst@cn.fujitsu.com>
> ---
> Documentation/kdump/kdump.txt | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
> index 88ff63d..9a77247 100644
> --- a/Documentation/kdump/kdump.txt
> +++ b/Documentation/kdump/kdump.txt
> @@ -392,7 +392,7 @@ 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.
> + kernel or specify nr_cpus=1 option while loading dump-capture kernel.
IIRC, ARCHes like ppc don't have nr_cpus yet, maxpcus is necessary. So
either you explicitly tell which can use nr_cpus and which can only use
maxcpus option, or drop this patch for now.
>
> * 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] 3+ messages in thread
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