%ifutil

[Michele Baldessari <michele@xxxxxxxxxx>]

Hi folks,

I am slowly working on replacing all our internal scripts to collect network
statistics. One value that sar gives out is %ifutil, which is defined as
follows:
"""
Utilization percentage of the network interface. For half-duplex interfaces,
utilization is calculated using the sum  of  rxkB/s  and txkB/s as a percentage
of the interface speed. For full-duplex, this is the greater of rxkB/S or
txkB/s.
"""

Code:
double compute_ifutil(struct stats_net_dev *st_net_dev, double rx, double tx)
{       
                unsigned long long speed;
                
                if (st_net_dev->speed) {
                 
                                speed = st_net_dev->speed * 1000000;
                 
                                if (st_net_dev->duplex == C_DUPLEX_FULL) {
                                                /* Full duplex */
                                                if (rx > tx) {
                                                                return (rx * 
800 / speed);
                                                }
                                                else {
                                                                return (tx * 
800 / speed);
                                                }
                                }
                                else {  
                                                /* Half duplex */
                                                return ((rx + tx) * 800 / 
speed);
                                }
                }
                                
                return 0;
}

Two questions:
1) Would it be ok to add this to the Linux PMDA or do you feel this is 
something to be taken care of
by higher-level apps/tools or via some combined metric?
2) In case the answer to 1) is 'it is ok', is the above calculation ok? I'm not 
entirely convinced.
I'd personally split it in %rx_ifutil and %tx_ifutil. Thoughts?

Cheers,
Michele
-- 
Michele Baldessari            <michele@xxxxxxxxxx>
C2A5 9DA3 9961 4FFB E01B  D0BC DDD4 DCCB 7515 5C6D