Cc: Andi Kleen <andi@...>, Joe Malicki <jmalicki@...>, David Miller <davem@...>, <johnpol@...>, <netdev@...>, <linux-kernel@...>, <juhlenko@...>, <sammy@...>
So... if using ping on your machine has direct an noticeable effect on cpu load, problem is elsewhere
(if no ping is running, you dont have skb timestamping, but still getnstimeofday() is the top function in oprofile)
1) Do you have any netfilter rule using xt_time ?
(This module also calls __net_timestamp(skb))
2) You maybe have a bad program that do something expensive relative to kernel time services.
bad_program()
{
while (1) {
struct timeval t0,t1;
gettimeofday(&tv0, NULL); // or whatever function that calls getnstimeofday()
do_small_work();
gettimeofday(&tv1, NULL); // or whatever function that calls getnstimeofday()
add_stat_event(&tv1, &tv0);
}
> 2)Usefullness of this option. What is a difference if on almost idle machine
Your setup is probably not common.
You want a PersonnalComputer class machine acts as a SuperCiscoDevice(TM),
while most PC machines dont use more than 10% of CPU power in average...
Many existing programs depend on current SO_TIMESTAMP.
We wont break them to solve a particular problem (yet to be demonstrated)
>
kernel already provides nanosecond resolution :)
Check SO_TIMESTAMPNS and SCM_TIMESTAMPNS
