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authorDave Hansen <dave@linux.vnet.ibm.com>2008-10-15 22:01:46 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-16 11:21:31 -0700
commit22b8ce94708f7cdf0b04965c6f7443dfd374c35c (patch)
treee2d5b60e9b881cf251185b23c3853c8b3e52d42a /Documentation
parent0c2d64fb6cae9aae480f6a46cfe79f8d7d48b59f (diff)
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profiling: dynamically enable readprofile at runtime
Way too often, I have a machine that exhibits some kind of crappy behavior. The CPU looks wedged in the kernel or it is spending way too much system time and I wonder what is responsible. I try to run readprofile. But, of course, Ubuntu doesn't enable it by default. Dang! The reason we boot-time enable it is that it takes a big bufffer that we generally can only bootmem alloc. But, does it hurt to at least try and runtime-alloc it? To use: echo 2 > /sys/kernel/profile Then run readprofile like normal. This should fix the compile issue with allmodconfig. I've compile-tested on a bunch more configs now including a few more architectures. Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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+What: /sys/kernel/profile
+Date: September 2008
+Contact: Dave Hansen <dave@linux.vnet.ibm.com>
+Description:
+ /sys/kernel/profile is the runtime equivalent
+ of the boot-time profile= option.
+
+ You can get the same effect running:
+
+ echo 2 > /sys/kernel/profile
+
+ as you would by issuing profile=2 on the boot
+ command line.
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