From: Petr Mladek <pmladek@suse.cz>
To: Tom Zanussi <tom.zanussi@linux.intel.com>,
Steven Rostedt <rostedt@goodmis.org>
Cc: Jiri Kosina <jkosina@suse.cz>, linux-kernel@vger.kernel.org
Subject: [BUG] ftrace: support for SOFT_DISABLE to syscall events caused huge slowdown of ftrace startup test
Date: Tue, 03 Dec 2013 18:16:09 +0100 [thread overview]
Message-ID: <1386090969.1603.72.camel@pathway.suse.cz> (raw)
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
next reply other threads:[~2013-12-03 17:16 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-03 17:16 Petr Mladek [this message]
2013-12-03 17:41 ` [BUG] ftrace: support for SOFT_DISABLE to syscall events caused huge slowdown of ftrace startup test Steven Rostedt
2013-12-03 20:46 ` Tom Zanussi
2013-12-03 22:32 ` Tom Zanussi
2013-12-04 12:47 ` Petr Mladek
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