On 08/03/16 at 10:05am, "Zhou, Wenjian/???" 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 at 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 at lists.infradead.org > >>http://lists.infradead.org/mailman/listinfo/kexec > > > > > > > -- > Thanks > Zhou > >
