PCIe-lat-operation.txt

Operation ordering

prequisition:
	vi /proc/cpuinfo
search flags,and if there is a "stdscp",then your computer can use this modules

enter:
	cd /home/aqiu/pcie-latency


<1>#sudo su

<2>#lspci
	/*find the pcie devices*/

<3>#lspci -nn -s 00:05.0
	/*find the Vendor ID and Device ID*/

<2 + 3>  #lspci -x
00: f4 1a 00 10 07 04 10 00 00 00 00 02 00 00 00 00
1af4: 1000

<4>#echo 0000:00:05.0 > /sys/bus/pci/devices/0000\:00\:05.0/driver/unbind
	/*If the device you want to measure is currently bound to a driver, release it*/


<5>#make
	/*
	error: vmalloc undeclared
	solution: add following code in pcie-latency.c
				#include <linux/vmalloc.h>
	*/

<6>#insmod ./pcie-lat.ko ids=1af4:1000
	/*1af4:1000  Vendor ID and Device ID*/

<7>ruby measure.rb -p 00:05.0 -l 1000000 -b 1 -o 0x0
	/* I got a error:Caught exception: Invalid argument - /sys/bus/pci/devices/0000:00:05.0/pcie-lat/00:05.0/pcielat_measure

	reason: different pc have different bar

	solution: 
			 change command with (-b 0 ----> -b 1):ruby measure.rb -p 00:05.0 -l 1000000 -b 1 -o 0x0
	*/

	```shell
ruby measure.rb -p 08:10.0 -l 1000000 -b 0 -o 0x0

> TSC freq:     2294470000.0 Hz
> TSC overhead: 52 cycles
> Device:       08:10.0
> BAR:          0
> Offset:       0x0
> Loops:        1000000
>
>        | Results (1000000 samples)
> ------------------------------------------------------
> Mean   |   3628.02 cycles |   1581.20 ns
> Stdd   |     30.69 cycles |     13.37 ns
>
>
>        | 3σ Results (995274 samples, 0.005% discarded)
> ------------------------------------------------------
> Mean   |   3627.52 cycles |   1580.99 ns
> Stdd   |     27.69 cycles |     12.07 ns
>
> writing 3σ values (in ns) to file...
```

<8>python hist.py lat_1000000_loops_3sigma.csv

Requirement:
			For Python2x:
			sudo apt-get install python-numpy
			sudo apt-get install python-matplotlib

			For Python3x:
			sudo apt-get install python3-numpy
			sudo apt-get install python3-matplotlib
##Remarks##
* pcie-lat only works on 64 Bit x86 architectures.
* Look at the comments inside the source files for more in-depth explanations.
* Some debug/runtime information can be viewed via `dmesg`.


error : CONFIG_X86_X32 enabled but no binutils support
answer: 	can't have space in the path