Hi, Dave
Thanks for the comment.
在 2020年08月19日 16:53, Dave Young 写道:
Hi Lianbo,
On 08/12/20 at 02:32pm, Lianbo Jiang wrote:
> Sometimes, debugging the kdump service failure becomes very challenging
> because there is no complete debugging information, which requires
> modification of the options or the scripts like kdumpctl, mkdumprd, etc
> to collect the information for troubleshooting.
>
> That means users have to wait for the next failure so that they can
> capture the additional information, which could waste valuable time.
>
> This patch series will add the debugging messages and save them to a
> file. It includes the following patches:
>
> [1] [PATCH 1/2] kdumpctl/mkdumprd: add 'set -x' to output debugging
> information to a file
> [2] [PATCH 2/2] kdumpctl: add the '-d' option to enable the kexec loading
> debugging messages
[2] should be good, but for [1], I'm not sure if this can make kdump
service startup even slower. Have you compared the performance
with/without the change?
That will definitely affect performance although I haven't measured it
exactly.
I will provide the performance data when I post it again.
A good option is that we can accurately output useful messages in the kdump code,
which has the least impact on performance.
BTW, "set -x" usually means too much noise, we may need to
have some
loglevel, export fine grained logs if possible by default, the export the whole
"set -x" logs when the logleve is set as max.
For the log level, usually, it doesn't enable the debug log, but it means that
we
will have to enable it manually and try to reproduce the problem again.
Another question is there is an option in dracut below:
--debug
output debug information of the build process
-v, --verbose
increase verbosity level (default is info(4))
For /sbin/mkdumprd debuggin, should we just use the dracut option for
dracut debug info?
The debug option(in dracut) also uses the 'set -x' as below:
[[ $debug ]] && {
export DRACUT_LOG_LEVEL=debug
export PS4='${BASH_SOURCE}@${LINENO}(${FUNCNAME[0]}): ';
set -x
}
There seems to be the same amount of log output.
Maybe you have tried to use logger, do you have other reason to drop
the
usage? With this patches applied, not sure if the original visible logs
in systemd journal will disappear or not.
The logger will output messages into the system log, I think that's fine.
But some users still hope to output the debug messages to a new log file
instead of the console or memory.
Thanks.
Lianbo
>
> Changes since v1:
> [1] Set default log path to '/var/log/kdump' instead of '/var/crash'
> [2] Add a timestamp to the debug log messages
> [3] Print a message to differentiate between the kdumpctl and mkdumprd log
>
> Lianbo Jiang (2):
> kdumpctl/mkdumprd: add 'set -x' to output debugging information to a
> file
> kdumpctl: add the '-d' option to enable the kexec loading debugging
> messages
>
> kdumpctl | 12 +++++++++++-
> mkdumprd | 10 ++++++++++
> 2 files changed, 21 insertions(+), 1 deletion(-)
>
> --
> 2.17.1
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Thanks
Dave