[dpdk-dev] How can I calculate/estimate pps(packet per seocond) and bps(bit per second) in DPDK pktg

[최익성]

 Dear Polehn, Mike A and DPDK experts. 
 
Thank you very much for your previous advice and answer.
 
I used the method you proposed.
 
I dont't understand that the data rate includes preamble and inter-packet gap since the preamble and the inter-packet gap are not packet data.
 
There are significant packet bursts in DPDK packet stream.
 
I used average value of gps/pps history (128 history).
 
It works well.
 
Thank you very much.
 
Sincerely Yours,
 
Ick-Sung Choi.
 
 
-----Original Message-----
From: "Polehn, Mike A"<mike.a.polehn at intel.com> 
To: "???"<pnk003 at naver.com>; "Wiles, Keith"<keith.wiles at intel.com>; "Van Haaren, Harry"<harry.van.haaren at intel.com>; "dev at dpdk.org"<dev at dpdk.org>; 
Cc: 
Sent: 2015-11-04 (수) 23:21:54
Subject: RE: [dpdk-dev] How can I calculate/estimate pps(packet per seocond) and bps(bit per second) in DPDK pktg
 








The change in tsc value from rte_rdtsc() needs to be multiplied by the scale to convert from clocks to get change in seconds.

For example from below:

 

elapse_us = (rte_rdtsc() - entry->tsc_first_packet) * flow_time_scale_us;

 

The bit rate requires the number of bytes passed in the time period then adjusted by the overhead of the number of packets transferred in the time period.

 

#define FLOWD_PERF_PACKET_OVERHEAD 24 /* CRC + Preamble + SOF + Interpacket gap */






Bits = (Bytes + (Packets*FLOWD_PERF_PACKET_OVERHEAD)) * 8;

Data_Rate = (((double)Bits) / Time_us) * 1e6;






Integer math is very tricky and often is not any faster than floating point math when using multiplies except on the very low performance processors.

 

Mike

 



From:
최익성 [mailto:pnk003 at naver.com]


Sent: Tuesday, November 3, 2015 5:45 PM

To: Polehn, Mike A; Wiles, Keith; Van Haaren, Harry; dev at dpdk.org

Subject: RE: [dpdk-dev] How can I calculate/estimate pps(packet per seocond) and bps(bit per second) in DPDK pktg



 


Dear  Wiles, Keith ,  Van Haaren, Harry,  Polehn, Mike A,  Stephen Hemminger, Kyle Larose, and DPDK experts. 

 

I really appreciate for your precious answers and advices.

 

I will find and study the corresponding codes and CRC checking.

 

 

Last night, I tried to estimate bps and pps by using the following code.

 

 

// rte_distributor_process() gets 64 mbufs packets at a time.

// rte_distributor_process() gets packets from Intel® 82599ES 10 Gigabit Ethernet 2 port Controller (2 10gbE ports).

 

int  rte_distributor_process(struct rte_distributor *d, struct rte_mbuf **mbufs, unsigned num_mbufs)

{

        uint64_t ticks_per_ms = rte_get_tsc_hz()/1000 ;

        uint64_t ticks_per_s = rte_get_tsc_hz() ;

        uint64_t ticks_per_s_div_8 = rte_get_tsc_hz()/8 ;

        uint64_t cur_tsc = 0, last_tsc = 0, sum_len, bps, pps ;

 

        cur_tsc = rte_rdtsc();

 

        sum_len = 0 ; 

        for (l=0; l < num_mbufs; l++ ) { sum_len += mbufs[l]->pkt_len ; }

 

        if ((cur_tsc - last_tsc)!=0) { 

               bps = (sum_len * ticks_per_s_div_8 ) / (cur_tsc - last_tsc) ; 

               pps = num_mbufs * ticks_per_s / (cur_tsc - last_tsc) ; 

        } else bps = pps = 0 ;

 

        last_tsc = cur_tsc ;

}

 

I got  max. bit per second = 6,835,440,833 for 20 Gbps 1500 bytes packet traffic, and got max. bit per second = 6,808,524,220 for 2 Gbps 1500 bytes packet traffic.

 

I guess there can be packet burst, however the estimated value has too many errors.

 

I will try the methods you proposed. 

 

Thank you very much.

 

Sincerely Yours,

 

Ick-Sung Choi.


 


-----Original Message-----

From: "Polehn, Mike A"<mike.a.polehn at intel.com>


To: "Wiles, Keith"<keith.wiles at intel.com>; "Van Haaren, Harry"<harry.van.haaren at intel.com>; "???"<pnk003 at naver.com>; "dev at dpdk.org"<dev at dpdk.org>;


Cc: 

Sent: 2015-11-04 (수) 00:59:34

Subject: RE: [dpdk-dev] How can I calculate/estimate pps(packet per seocond) and bps(bit per second) in DPDK pktg

 

I used the following code snip-it with the i40e device, with 1 second sample time had very high accuracy for IPv4 UDP packets:




#define FLOWD_PERF_PACKET_OVERHEAD 24 /* CRC + Preamble + SOF + Interpacket gap */


#define FLOWD_REF_NETWORK_SPEED 10e9 



double Ave_Bytes_per_Packet, Data_Rate, Net_Rate; 

uint64_t Bits; 

uint64_t Bytes = pFlow->flow.n_bytes - pMatch_Prev->flow.n_bytes; 

uint64_t Packets = pFlow->flow.n_packets - pMatch_Prev->flow.n_packets; 

uint64_t Time_us = pFlow->flow.flow_time_us - pMatch_Prev->flow.flow_time_us; 



if (Bytes == 0) 

Ave_Bytes_per_Packet = 0.0; 

else 

Ave_Bytes_per_Packet = ((double)Bytes / (double)Packets) + 4.0; 



Bits = (Bytes + (Packets*FLOWD_PERF_PACKET_OVERHEAD)) * 8; 

if (Bits == 0) 

Data_Rate = 0.0; 

else 

Data_Rate = (((double)Bits) / Time_us) * 1e6; 



if (Data_Rate == 0.0) 

Net_Rate = 0.0; 

else 

Net_Rate = Data_Rate / FLOWD_REF_NETWORK_SPEED; 



For packet rate: double pk_rate = (((double)Packets)/ ((double)Time_us)) * 1e6; 



To calculate elapsed time in DPDK app, used CPU counter (will not work if counter is being modified):




Initialization: 

double flow_time_scale_us; 

... 

flow_time_scale_us = 1e6/rte_get_tsc_hz(); 



Elapsed time (uSec) example: 



elapse_us = (rte_rdtsc() - entry->tsc_first_packet) * 

flow_time_scale_us; /* calc total elapsed us */ 



-----Original Message----- 

From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Wiles, Keith


Sent: Tuesday, November 3, 2015 6:33 AM 

To: Van Haaren, Harry; ???; dev at dpdk.org 

Subject: Re: [dpdk-dev] How can I calculate/estimate pps(packet per seocond) and bps(bit per second) in DPDK pktg




On 11/3/15, 8:30 AM, "Van Haaren, Harry" <harry.van.haaren at intel.com> wrote:




>Hi Keith, 

> 

>> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Wiles, Keith


><snip> 

>> Hmm, I just noticed I did not include the FCS bytes. Does the NIC 

>> include FCS bytes in the counters? Need to verify that one and if not then it becomes a bit more complex.


> 

>The Intel NICs count packet sizes inclusive of CRC / FCS, from eg the ixgbe/82599 datasheet:


>"This register includes bytes received in a packet from the <Destination Address> field through the <CRC> field, inclusively."




Thanks I assumed I had known that at the time :-) 

> 

>-Harry 

> 





Regards, 

Keith