Re: [dpdk-dev] running dpdk application on the same machine with other none dpdk application

[Shirley Avishour <shirley@imvisiontech.com>]

Hi Rami,
In order to isolate the required core we add isolcpus to the grub:
GRUB_CMDLINE_LINUX_DEFAULT="default_hugepagesz=2M hugepagesz=1G hugepages=8
isolcpus=1-5"

To disable hyperthreading for these cores we add command to the rcl.local:
(which in fact disables the peer logical core)
echo 0 > /sys/devices/system/cpu/cpu23/online
echo 0 > /sys/devices/system/cpu/cpu24/online
echo 0 > /sys/devices/system/cpu/cpu25/online
echo 0 > /sys/devices/system/cpu/cpu26/online
echo 0 > /sys/devices/system/cpu/cpu27/online

our dpdk application runs on cores 1-5: --lcores='(0,4-6)@5,1@1,2@2,3@3,7@4'

But cpu isolation does not prevent from kernel processes/threads from
running on isolated cpus.
Running java based applications on the same server with a dpdk based
application has an impact on the dpdk performance.
Probably since the JVM generates kernel based processes. It can be either
GC (garbage collection) or other operations.
We are looking for a way to prevent these kernel threads from using the
isolated cores.

Thanks,
Shirley.




On Wed, Jan 30, 2019 at 8:09 AM Rami Rosen <ramirose@gmail.com> wrote:

> Hi, Shirley
>
> >In order to do that we isolated the dpdk application cores and disabled
> hyperthreading for those cores.
> >we are using 5 cores for the dpdk application (which is in fact 10 since
> hyperthreading is disabled).
>
> Short clarification question: did you do it with EAL paramater ?
>
> Was it with
> -l CORELIST / --lcores COREMAP EAL parameter ?
>
> Did you try also the isolcpus Linux kernel parameter in order to isolate
> cores from the general Linux scheduler?
>
> Regards,
> Rami Rosen
>
>
> On Tue, Jan 29, 2019 at 6:32 PM Shirley Avishour <shirley@imvisiontech.com>
> wrote:
>
>> Hi,
>> We are trying to run a dpdk based application one the same machine with
>> other java based applications.
>> In order to do that we isolated the dpdk application cores and disabled
>> hyperthreading for those cores.
>> But sporadically we encounter misses over the interface.
>> We are running on a single socket cpu with 44 hyperthreaded cores.
>> we are using 5 cores for the dpdk application (which is in fact 10 since
>> hyperthreading is disabled).
>> My guess is that probably GC (garbage collection) running from the kernel
>> and perhaps over the isolated threads causing the misses.
>> Is there a way to solve this issue? Is there a way to isolate cores for
>> kernel processes/threads?
>> Thanks in advance,
>> Shirley.
>>
>
>
> --
> regards,
> Rami Rosen
>