Messages in this thread | | | Subject | [BUG] ftrace: support for SOFT_DISABLE to syscall events caused huge slowdown of ftrace startup test | From | Petr Mladek <> | Date | Tue, 03 Dec 2013 18:16:09 +0100 |
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Hi,
I tested my ftrace-related patches and enabled also the startup test:
CONFIG_FTRACE_SELFTEST=y CONFIG_FTRACE_STARTUP_TEST=y
On today's kernel/git/tip/tip.git, the boot "freezed" for 1 minute when doing "Testing event system syscalls".
A bisect pointed finger to the commit d562aff93bfb530b099 (tracing: Add support for SOFT_DISABLE to syscall events).
It seems that the culprit are the "synchronize_sched" calls added to "unreg_event_syscall_enter" and "unreg_event_syscall_exit" functions. They are called 2312 times during the boot here and are responsible for the delay.
I wonder if it might cause slowdown also at runtime.
I am going to look deeper into the code and eventually come up with a solution. But it might take some time. I am still newbie in the kernel development. Any hints or tips are welcome ;-)
Best Regards, Petr
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