On Mon, 2007-30-07 at 18:37 -0700, David Miller wrote: > Relatively speaking, the acpi_pm numbers are at least consistent and > about as much as so as jiffies. Jiffies numbers are also possibly > better, at least in part, because of the decreased accuracy and errors > propagating.
I am not sure jiffies gives innacurate results. It gives the best performance on the dual xeon i tested on, all the time. Very consistent. On its accuracy: I was able to validate it With pktgen generating traffic and some external hardware tool capturing the interpacket gaps etc. > tsc acts as expected, since every time your cpu changes power > management state (which it is going to do dynamically) the TSC > rates change and thus the accuracy goes into outer-space. Robert was saying he had even more bizare results with opteron given the NUMA nature. > There really isn't much that can be done by any of this. These issues > exist because of hardware limitations, nobody bothered to build > x86/x86_64 systems with a system wide TICK register that is both > impervious to cpu frequence scaling and also cheap to access. > > So the above is what we basically have to live with :-) That is a bummer. I am going to test with hpet when i get the chance and perhaps turn off all the other sources if nothing good comes out; i need my numbers ;-> cheers, jamal - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
