On Tue, 14 Dec 2010 19:55:08 +0100, Peter Zijlstra said: > 10*HZ = 10 seconds > (10*HZ) / 1024 ~= 10 milliseconds from include/asm-generic/param.h (which is included by x86) #ifdef __KERNEL__ # define HZ CONFIG_HZ /* Internal kernel timer frequency */ # define USER_HZ 100 /* some user interfaces are */ # define CLOCKS_PER_SEC (USER_HZ) /* in "ticks" like times() */ #endif Note that HZ isn't USER_HZ or CLOCKS_PER_SEC - it's CONFIG_HZ, which last I checked is still user-settable. If not, then there needs to be a massive cleanup of Kconfig and defconfig: % grep HZ .config CONFIG_NO_HZ=y # CONFIG_HZ_100 is not set # CONFIG_HZ_250 is not set # CONFIG_HZ_300 is not set CONFIG_HZ_1000=y CONFIG_HZ=1000 So you're not guaranteed that 10*HZ is 10 seconds. 10*USER_HZ, sure. But not HZ.
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