[dpdk-users] build dpdk for a cpu that doesn't support avx

[dpdk-users] build dpdk for a cpu that doesn't support avx

[Alex Kiselev]

Hi.

Is it possible to build DPDK application  on a machine that do have AVX support
for use at another machine that doesn't have AVX feature?

Thanks.

Re: [dpdk-users] build dpdk for a cpu that doesn't support avx

[Alex Kiselev]

It looks like I've found a way:

I edited $RTE_SDK/config/defconfig_x86_64-native-linuxapp-gcc
  CONFIG_RTE_MACHINE="x86-64"

and then I used
  make EXTRA_CFLAGS="-march=x86-64 -mpopcnt -mmmx -msse -msse2 -msse3 -mssse3 -msse4.1 -msse4.2 -mfpmath=sse -mpopcnt"

The application has started successfully.
But I am wondering, maybe I've missed something and there are potential bugs in this way?

> Hi.

> Is it possible to build DPDK application  on a machine that do have AVX support
> for use at another machine that doesn't have AVX feature?

> Thanks.

--
Alex

Re: [dpdk-users] build dpdk for a cpu that doesn't support avx

[Van Haaren, Harry]

> -----Original Message-----
> From: users [mailto:users-bounces@dpdk.org] On Behalf Of Alex Kiselev
> Sent: Thursday, February 21, 2019 3:33 PM
> To: users@dpdk.org
> Subject: Re: [dpdk-users] build dpdk for a cpu that doesn't support avx
> 
> It looks like I've found a way:
> 
> I edited $RTE_SDK/config/defconfig_x86_64-native-linuxapp-gcc
>   CONFIG_RTE_MACHINE="x86-64"
> 
> and then I used
>   make EXTRA_CFLAGS="-march=x86-64 -mpopcnt -mmmx -msse -msse2 -msse3 -mssse3
> -msse4.1 -msse4.2 -mfpmath=sse -mpopcnt"
> 
> The application has started successfully.
> But I am wondering, maybe I've missed something and there are potential bugs
> in this way?
> 
> > Hi.
> 
> > Is it possible to build DPDK application  on a machine that do have AVX
> support
> > for use at another machine that doesn't have AVX feature?
> 
> > Thanks.


Using -march to manually tune should work fine, just be aware of mistakes made; this is an error prone method..

As per the GCC docs, you can target specific CPU families, and the optimal flags will be selected:
https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html

Example:  -march=goldmont-plus

With make, EXTRA_CFLAGS="-march=NAME-HERE" should work
With Meson, cd <build_dir> && meson configure -Dc_args="-march=NAME-HERE"

I guess there's a prettier method for meson, but the above works here :)

Hope that helps, -Harry

Re: [dpdk-users] build dpdk for a cpu that doesn't support avx

[Alex Kiselev]

>> -----Original Message-----
>> From: users [mailto:users-bounces@dpdk.org] On Behalf Of Alex Kiselev
>> Sent: Thursday, February 21, 2019 3:33 PM
>> To: users@dpdk.org
>> Subject: Re: [dpdk-users] build dpdk for a cpu that doesn't support avx

>> It looks like I've found a way:

>> I edited $RTE_SDK/config/defconfig_x86_64-native-linuxapp-gcc
>>   CONFIG_RTE_MACHINE="x86-64"

>> and then I used
>>   make EXTRA_CFLAGS="-march=x86-64 -mpopcnt -mmmx -msse -msse2 -msse3 -mssse3
>> -msse4.1 -msse4.2 -mfpmath=sse -mpopcnt"

>> The application has started successfully.
>> But I am wondering, maybe I've missed something and there are potential bugs
>> in this way?

>> > Hi.

>> > Is it possible to build DPDK application  on a machine that do have AVX
>> support
>> > for use at another machine that doesn't have AVX feature?

>> > Thanks.


> Using -march to manually tune should work fine, just be aware of
> mistakes made; this is an error prone method..

> As per the GCC docs, you can target specific CPU families, and the optimal flags will be selected:
> https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html

> Example:  -march=goldmont-plus

> With make, EXTRA_CFLAGS="-march=NAME-HERE" should work
> With Meson, cd <build_dir> && meson configure -Dc_args="-march=NAME-HERE"

> I guess there's a prettier method for meson, but the above works here :)

> Hope that helps, -Harry

Yes, it helped. Thank you. 
I've switched to using EXTRA_CFLAGS="-march=westmere"

--
Alex