Messages in this thread | | | Subject | register_timer_hook fails on realtime kernel with CONFIG_PROFILE_NMI | From | John Kacur <> | Date | Sun, 06 Aug 2006 01:59:37 -0400 |
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Hi, I wrote a "Very Simple Timer Notification Module", which calls register_timer_hook to register a function to be called using the timer interrupt. This is essentially what OProfile would do in timer interrupt mode. The standard kernel allows you to do this even if CONFIG_PROFILE_NMI is defined but the realtime kernel does not. With the realtime kernel register_timer_hook succeeds but the timer hooks is never called. From patch-2.6.17-rt8 the following modifies linux/include/linux/clockchips.h +#ifndef CONFIG_PROFILE_NMI +#define CLOCK_CAP_PROFILE 0x000008 +#else +#define CLOCK_CAP_PROFILE 0x000000 +#endif
So, it's simple enough to work around, by just making CLOCK_CAP_PROFILE 0x000008 regardless of whether CONFIG_PROFILE_NMI is defined or not, but I would like to understand the intention of the authors here. Is there a good reason to disallow the timer interrupt mode of profiling if CONFIG_PROFILE_NMI is defined? (other than arguing that NMI profiling is superior)
I have included vstnm.tar.bz2 in case it is of any help examinig the problem. Just do: tar xjf vstnm.tar.bz2 cd vstnm make make install then use the script load_vstnm to load the module and unload_vstnm to unload the module. If the timer_tick function is called it will print a rate limited message to the console that it was called.
Thank you
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