[LTP] [RFC PATCH] starvation: set a baseline for maximum runtime

Li Wang liwang@redhat.com
Wed Nov 27 05:15:20 CET 2024


On Tue, Nov 26, 2024 at 7:23 PM Cyril Hrubis <chrubis@suse.cz> wrote:

> Hi!
> > Well, we have not achieved a reliable way to detect debug kernels in LTP.
> > While I looking at our RHEL9 kernel config file. The general kernel also
> > enables things like "CONFIG_DEBUG_KERNEL=y".
>
> The slowdown is likely to be realated to a few specific debug options
> such as debugging for mutexes, spinlocks, lists, etc. I guess that the
> most interesting information would be a difference in the debug options
> between the general kernel and the debug kernel. Hopefully we can put
> together a set of debug options that are cause the test to run over
> slow.
>


I have carefully compared the differences between the general
kernel config-file and the debug kernel config-file.

Below are some configurations that are only enabled in the debug
kernel and may cause kernel performance degradation.

The rough thoughts I have is to create a SET for those configurations,
If the SUT kernel maps some of them, we reset the timeout using the
value multiplier obtained from calibration.

e.g. if mapped N number of the configs we use (timeout * N) as the
max_runtime.

Or next, we extract this method to the whole LTP timeout setting if
possible?


#Lock debugging:
CONFIG_PROVE_LOCKING
CONFIG_LOCKDEP
CONFIG_DEBUG_SPINLOCK

#Mutex debugging
CONFIG_DEBUG_RT_MUTEXES=y
CONFIG_DEBUG_MUTEXES=y

#Memory debugging:
CONFIG_DEBUG_PAGEALLOC
CONFIG_KASAN
CONFIG_SLUB_RCU_DEBUG

#Tracing and profiling:
CONFIG_TRACE_IRQFLAGS
CONFIG_LATENCYTOP
CONFIG_DEBUG_NET

#Filesystem debugging:
CONFIG_EXT4_DEBUG
CONFIG_QUOTA_DEBUG

#Miscellaneous debugging:
CONFIG_FAULT_INJECTION
CONFIG_DEBUG_OBJECTS


-- 
Regards,
Li Wang


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