irq_balance_habrahabr.sh

irq_balance_habrahabr.sh

#!/bin/bash

# from http://habrahabr.ru/post/108240/
ncpus=`grep -ciw ^processor /proc/cpuinfo`
test "$ncpus" -gt 1 || exit 1

n=0
for irq in `cat /proc/interrupts | grep eth | awk '{print $1}' | sed s/\://g`
do
    f="/proc/irq/$irq/smp_affinity"
    test -r "$f" || continue
    cpu=$[$ncpus - ($n % $ncpus) - 1]
    if [ $cpu -ge 0 ]
            then
                mask=`printf %x $[2 ** $cpu]`
                echo "Assign SMP affinity: eth queue $n, irq $irq, cpu $cpu, mask 0x$mask"
                echo "$mask" > "$f"
                let n+=1
    fi
done

@hit0ri - The problem with nrpoc is that if you are using isolcpu/nohz_full/rcu_nocbs it won't count those CPUs. Example case, we set nohz_full=1-15 isolcpus=1-15 rcu_nocbs=1-15 and use core 0 for OS, nproc returns 1 instead of 16.

ncpus=`grep -ciw ^processor /proc/cpuinfo` works fine.

(dont ask me why, hehe) On php

	$numCpus = 1;
	$cpuinfo = file_get_contents('/proc/cpuinfo');
	preg_match_all('/^processor/m', $cpuinfo, $matches);
	$numCpus = count($matches[0]);
	$ethint = array();
	$baseethint = array();
	foreach(explode(PHP_EOL, file_get_contents("/proc/interrupts")) as $interrupt){
		foreach($interfaces as $eth){
			if (strpos($interrupt, $eth) !== false) {
				$name = @end(explode(" ", $interrupt));
				$ethint[$name] = (int)explode(":", $interrupt)[0];
				$basename = explode("-", $name)[0];
				if ($basename != $name) {
					$baseethint[$basename] = 1;
				}
			}
		}
	}
	$counter = 0;
	foreach($ethint as $name => $interrupt){
		$core = $counter % $numCpus;
		$basename = explode("-", $name)[0];
		if ($basename != $name || !array_key_exists ($basename, $baseethint)) {
			echo "\t".$name." - IRQ-".$interrupt." => ".$core."\n";
			file_put_contents("/proc/irq/".$interrupt."/smp_affinity", dechex(pow(2,$core)));
			$counter++;
		}
	}