Editing BogoMips (section)

== Timer-based delays ==

In 2012, [[ARM Holdings|ARM]] contributed a new <code>udelay</code> implementation allowing the system timer built into many ARMv7 CPUs to be used instead of a busy-wait loop.  This implementation was released in Version 3.6 of the [[Linux kernel]].<ref>{{cite web|title=ARM: 7452/1: delay: allow timer-based delay implementation to be selected|last=Deacon|first=Will|url=https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d0a533b18235d36206b9b422efadb7cee444dfdb}}</ref> Timer-based delays are more robust on systems that use [[Dynamic frequency scaling|frequency scaling]] to dynamically adjust the processor's speed at runtime, as <code>loops_per_jiffies</code> values may not necessarily scale linearly.  Also, since the timer frequency is known in advance, no calibration is needed at boot time.

One side effect of this change is that the BogoMIPS value will reflect the timer frequency, not the CPU's core frequency.  Typically the timer frequency is much lower than the processor's maximum frequency, and some users may be surprised to see an unusually low BogoMIPS value when comparing against systems that use traditional busy-wait loops.