glennklockwood

ubuntu@ubuntu:~$ sudo dmidecode
# dmidecode 3.0
Getting SMBIOS data from sysfs.
SMBIOS 3.0.0 present.
Table at 0x8AF1D000.

Handle 0x0000, DMI type 16, 23 bytes
Physical Memory Array
	Location: System Board Or Motherboard
	Use: System Memory

glennklockwood

#include <stdio.h>
#include <sched.h>

int main( int argc, char**argv )
{
#pragma omp parallel
    {
        printf( "Hello world from thread %d of %d running on cpu %2d!\n", 
            omp_get_thread_num()+1, 
            omp_get_num_threads(),

glennklockwood

#!/usr/bin/env python
"""Vary resistance on a digital potentiometer and measure the effect using
   an analog-digital converter"""
import spi # from https://github.com/glennklockwood/raspberrypi
import time

### use two independent SPI buses, but daisy chaining then is also valid
adc = spi.SPI(clk=18, cs=25, mosi=24, miso=23, verbose=False)
digipot = spi.SPI(clk=19, cs=13, mosi=26, miso=None, verbose=False)

glennklockwood

• The Python interpreter is not thread safe, so multithreading doesn't actually work (https://wiki.python.org/moin/GlobalInterpreterLock)
• Python contains features that are known to just plain not work
  • round doesn't actually round numbers. (https://docs.python.org/2/library/functions.html#round)  The notion of rounding a base10 number is fundamentally a base10 operation.  Why the hell would you try to do it in base 2?
  • os.path.commonprefix doesn't actually return valid paths (https://docs.python.org/2/library/os.path.html#os.path.commonprefix)
• Python's regex engine is obtuse and slow (http://glennklockwood.blogspot.com/2012/04/revisiting-perl-and-python-speed.html)
• MAJOR changes between MINOR revisions (2.6, 2.7)
  • subprocess.check_output
  • the "with" statement
• MAJOR changes between 2.0 and 3.0, like redefining fundamental math operations (https://www.python.org/dev/peps/pep-0238/)
• Time doesn't work

glennklockwood

#!/usr/bin/env python

import spi

### Initialize an SPI connection using BCM-mode pins 21, 20, and 16
max7219 = spi.SPI(clk=21, cs=20, mosi=16, miso=None, verbose=True)

### Zero out all registers
for cmd in range(16):
    packet = cmd << 8

glennklockwood

#!/usr/bin/env python
import RPi.GPIO as GPIO

input_pin = 14
output_pins = [22, 17, 5, 6, 13, 12, 25, 24, 27, 23]
GPIO.setmode(GPIO.BCM)
GPIO.setup(input_pin, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
for pin in output_pins:
    GPIO.setup(pin, GPIO.OUT)
i = 0

glennklockwood

#define _XOPEN_SOURCE 600
#include <unistd.h>
#include <fcntl.h>
int main(int argc, char *argv[]) {
    int fd;
    fd = open(argv[1], O_RDONLY);
    fdatasync(fd);
    posix_fadvise(fd, 0,0,POSIX_FADV_DONTNEED);
    close(fd);
    return 0;

glennklockwood

SELECT
	b.ts,
	b.ost_name,
	b.bytes_written - a.bytes_written,
	b.bytes_read - a.bytes_read
FROM
	(
		SELECT
			OST_DATA.TS_ID AS tsid,
			TIMESTAMP_INFO.`TIMESTAMP` AS ts,

glennklockwood

################################################################################
#
#   Run the IOR benchmark with the POSIX I/O API and one file per task
#
################################################################################
IOR START

### You MUST change the following parameters (see README.APEX)
    numTasks=32             # number of MPI processes to use.  You may choose to use one or more MPI processes per node.
    segmentCount=81920      # must be > fileSize / ( blockSize * numTasks ) where fileSize must be greater than 1.5 times the aggregate DRAM available for use by

glennklockwood

### bashrc/bash_profile for SunOS 5.10

# Solaris 10 lacks support for xterm-color (although it is provided in OpenCSW)
if [ "$TERM" == "xterm-color" ]; then
  export TERM=xterm
fi

alias ssh='ssh -X'
alias ls='ls -p'
alias md5='digest -a md5 -v'