tickless kernel , isolcpus,nohz_full,and rcu_nocbs
<p>I have add "isolcpus=3 nohz_full=3 rcu_nocbs=3" in grub.conf in 
RedHat 7.1 , kernel: linux 3.10.0-229 kernel and according to <a href="http://www.breakage.org/2013/11/15/nohz_fullgodmode/" rel="noreferrer">http://www.breakage.org/2013/11/15/nohz_fullgodmode/</a> 
I also execute the following command :</p>

<pre><code>cat /sys/bus/workqueue/devices/writeback/cpumask
f
echo 1 &gt; /sys/bus/workqueue/devices/writeback/cpumask

cat /sys/bus/workqueue/devices/writeback/numa
1
echo 0 &gt; /sys/bus/workqueue/devices/writeback/numa
</code></pre>

<p>The box has only 4 cpu cores , I run the following shell :</p>

<pre><code>watch -d 'cat /proc/interrupts'
</code></pre>

<p>look like work perfect , only cpu0 Local timer interrupts has 2000 per 2 secs,
the else cpu 1 to cpu 3  has less than 10 per 2 secs .</p>

<p>and then I test the following source :</p>

<pre><code>void *Thread2(void *param)
{
    pthread_detach(pthread_self());
    while( 1 ){
        sleep( 100000 ) ;
    }
}

void *Thread1(void *param)
{
    pthread_detach(pthread_self());
    while( 1 ){
        ;
    }
}

int main(int argc, char** argv)
{
    pthread_t tid ;
    pthread_create(&amp;tid , NULL, Thread1, (void*)(long)3);
    pthread_create(&amp;tid , NULL, Thread2, (void*)(long)3);

    while( 1 )
        sleep( 5 ) ;
}
</code></pre>

<p>and run it by :</p>

<pre><code>taskset -c 3 ./x1.exe
</code></pre>

<p>watch the output in :</p>

<pre><code>watch -d 'cat /proc/interrupts'
</code></pre>

<p>this time , cpu 3 get 10~30 Local timer interrupts per 2 secs , look fine,
then  I try to  run 2 thread1  by :</p>

<pre><code>pthread_create(&amp;tid , NULL, Thread1, (void*)(long)3);
pthread_create(&amp;tid , NULL, Thread1, (void*)(long)3);
</code></pre>

<p>then again run it :</p>

<pre><code>taskset -c 3 ./x1.exe
</code></pre>

<p>then I watch the core 3  has the same Local timer interrupts with core 0 ,
it is 2000 interrupts per 2 secs .</p>

<p>May I ask , why 2 very busy thread1 will cause core 3 has 
much more timer interrupts ?!  what cause this happened ?!
and how to modify it if it can be ?!</p>