On Fri, Feb 18, 2011 at 12:07 PM, erik quanstrom <quans...@quanstro.net> wrote: >> The high level overview is that it is stored in a shared page, mapped >> into each new process's memory space at start-up. The kernel is never >> entered; there are no context switches. The kernel has a timer that >> updates this page atomically. > > i wonder if that is uniformly faster. consider that > making reads of that page coherent enough on a > big multiprocessor and making sure there's not too > much interprocesser skew might be slower than a > system call.
are you claiming that enter system call look at kernel data page to figure out time exit system call could be faster than look at kernel data page to figure out time ? either way the memory accesses in the middle are the same.