X-Git-Url: https://git.kernel.dk/?a=blobdiff_plain;f=Documentation%2Fkdump%2Fkdump.txt;fp=Documentation%2Fkdump%2Fkdump.txt;h=b0eb27b956d95a2fc744d46b53647e05c7186e50;hb=ebf137f6703bc2cb055f4c000adc99e6ece4485d;hp=f7ef34065d540979ce04d2b425db07847971a434;hpb=3dfb4c1bf049535c82843fc4f9c37b635fe6494e;p=linux-2.6-block.git

diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index f7ef34065d54..b0eb27b956d9 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, you had better replace it with
   nr_cpus to save memory if supported by the current ARCH, such as x86.
 
+* You should enable multi-cpu support in dump-capture kernel if you intend
+  to use multi-thread programs with it, such as parallel dump feature of
+  makedumpfile. Otherwise, the multi-thread program may have a great
+  performance degradation. To enable multi-cpu support, you should bring up an
+  SMP dump-capture kernel and specify maxcpus/nr_cpus, disable_cpu_apicid=[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