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kdumpctl: bail out earlier in case of no reserved memory

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Some cloud people complained that VM boot speed is slower than
Ubuntu and other distributions, after some debugging, we found
that one of the causes is kdump service starts too slow(7seconds
according to the test result on the test VM), actually there is
no "crashkernel=X" specified. Although kdump service is parallel,
it affects the speed more or less especially on VMs with few cpus,
which is unacceptable. It is even worse when kdump initramfs is
built out in case of no reserved memory at first boot.

Commit afa4a35d3 ("kdumpctrl: kdump feasibility should fail if no
crash memory") can actually solve this issue.

This patch is a supplement of above-mentioned commit, we bail out
start() even earlier in case of no reserved memory.

Also made some cosmatic changes for check_crash_mem_reserved().

1) Before this patch
$ time kdumpctl start
No memory reserved for crash kernel.
Starting kdump: [FAILED]

real    0m0.282s
user    0m0.184s
sys     0m0.146s

2) After this patch
$ time kdumpctl start
No memory reserved for crash kernel
Starting kdump: [FAILED]

real    0m0.010s
user    0m0.008s
sys     0m0.001s

Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Acked-by: Pratyush Anand <panand@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
This commit is contained in:
Xunlei Pang 2017-04-29 09:15:00 +08:00 committed by Dave Young
parent 841ea5be0b
commit 071ea2a277
1 changed files with 12 additions and 10 deletions
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22
kdumpctl
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@ -1074,10 +1074,11 @@ is_secure_boot_enforced()
check_crash_mem_reserved()
{
MEM_RESERVED=$(cat /sys/kernel/kexec_crash_size)
if [ $MEM_RESERVED -eq 0 ]
then
echo "No memory reserved for crash kernel." >&2
local mem_reserved
mem_reserved=$(cat /sys/kernel/kexec_crash_size)
if [ $mem_reserved -eq 0 ]; then
echo "No memory reserved for crash kernel"
return 1
fi
@ -1163,6 +1164,12 @@ check_default_config()
start()
{
check_dump_feasibility
if [ $? -ne 0 ]; then
echo "Starting kdump: [FAILED]"
return 1
fi
check_config
if [ $? -ne 0 ]; then
echo "Starting kdump: [FAILED]"
@ -1172,13 +1179,8 @@ start()
if sestatus 2>/dev/null | grep -q "SELinux status.*enabled"; then
selinux_relabel
fi
save_raw
if [ $? -ne 0 ]; then
echo "Starting kdump: [FAILED]"
return 1
fi
check_dump_feasibility
save_raw
if [ $? -ne 0 ]; then
echo "Starting kdump: [FAILED]"
return 1