tune sysconfig to save 2nd kernel memory usage
The memory in 2nd kernel is limited, we need to use as less memory as we can
to ensure vmcore capturing ok.
I'm doing below improvements in this patch:
1)
numa support is not necessary for kdump kernel, so disable it by adding numa=off
to save some kernel mm memory usage.
2)
Also add udev.children-max=2 to cmdline to limit max udev chidren processes.
3)
For ppc64, ehea driver will by default enable multi queue feature which will
use a lot of memory. Almost each ppc machine will oom for network(ssh/nfs)
kdump. The module param use_mcs=0 is used to disable multi queue feature.
Tested these params on an IBM machine with 2 numa nodes which ooms even for
local dump to rootfs.
With this patch oom does not happen for local/ssh dump, but for nfs dump oom
still happens in the middle of makedumpfile vmcore copying. So there should be
other improvement yet.
For ehea driver there's other params we can use, but because it's hard to
measure the saved memory, I'm waiting for input from IBM people. We can add
them later.
Signed-off-by: Dave Young <dyoung@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Resolves: bz821997
dracut will mount rootfs for us, so we need not pass root to fstab again here.
Here remove the root-mount line.
This will depends on the root=cmdline is right, by default kdump will
inherit it from /proc/cmdline.
Vivek: add document about the assumption for the root= cmdline issue.
Signed-off-by: Dave Young <dyoung@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
