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KernelTrap: Debating Hertz

Jul 15, 2005, 08:30 (1 Talkback[s])

"The decision to change the default hertz in the 2.6 Linux kernel from 1000 to 250 continued to be discussed, until Linux creator Linus Torvalds finally had enough, 'get on with your lives. Realize that there is no 'perfect' value for HZ. 250 right now is somewhere reasonable, and for the extreme ends you can always choose your own.' He also dismissed concern over picking an ideal number that minimizes long-term time drift, 'long-term time drift is something that we inevitably have to use things like NTP to handle, if you want an exact clock.' Instead, he highlighted tasks that affect the short term, such as converting timevals into jiffies, 'in short-term things, the timeval/jiffie conversion is likely to be _bigger_ issue than the crystal frequency conversion. So we should aim for a HZ value that makes it easy to convert to and from the standard user-space interface formats. 100Hz, 250Hz and 1000Hz are all good values for that reason. 864 is not...'"

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