On Friday 20 April 2007 18:10:32 Christoph Lameter wrote: > > > Using local_t for per cpu counters is nice because then > > one can use cpu_local_add() etc. and that generates very good > > code at least on x86 and a few other architectures. That would > > then allow very cheap per CPU statistics, which are useful > > in a number of subsystems (like networking or MM code) > > Is the per cpu access fixed on x86? Last I checked it was not atomic.
With upcomming patches per cpu can be directly referenced using %fs/%gs Then cpu_local_add() etc will be a single instruction that is atomic regarding interrupts. > Uhhh.... Yuck. > > > Drawback will be larger code. > > Fix the per cpu area access instead? That doesn't help on architectures that don't have r-m-w instructions on memory (like all RISCSs) -Andi - To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
