Re: compile dpdk with no avx

On Wed, Nov 12, 2014 at 10:23:49AM -0500, Neil Horman wrote:

On Wed, Nov 12, 2014 at 02:24:10PM +0000, De Lara Guarch, Pablo wrote:

quoted

quoted

-----Original Message-----
From: dev [mailto:dev-bounces-VfR2kkLFssw@public.gmane.org] On Behalf Of Masaru Oki
Sent: Wednesday, November 12, 2014 1:48 PM
To: Yaron Illouz
Cc: <redacted>
Subject: Re: [dpdk-dev] compile dpdk with no avx

Hi,

Some libraries need AVX instruction, but if you don't use, it can disable.
  e.g. CONFIG_RTE_LIBRTE_IXGBE_PMD=n in config file.


2014-11-12 21:45 GMT+09:00 Yaron Illouz [off-list ref]:

quoted

Hi



I use dpdk in my product. I can't change my dpdk version.

I compile it on a server that have avx.

Most of the time, it run on machine that have avx, but not always.



When running the product on a machine with no avx, it crash on illegal
instruction.

The current solution is to build it on a computer with no avx.



Is there a compilation flag to disable avx? So it doesn't matter on
which computer I compiled it.

Basically, you are looking at cross-compiling DPDK. One thing you could do
 is go to one of the config files (i.e. defconfig_x86-64-native-linuxapp-gcc) 
and change CONFIG_RTE_MACHINE, from "native" to one of the
 micro-architectures that do not have avx, such as "wsm" (Westmere).

What version of dpdk are you running?  We fixed this a while ago with
commits 8777aabc538fdac24457958eaab929f33d6c4cdf and
074f54ad03ee0c84dcae235933e2b426208fe591.  They do runtime checking for
availability of the AVX and SSE3 instructions and only exeucte paths using those
instructions if the running cpu supports them.  Note that you are still required
to build for the default arch.
Neil

Hi Neil,

those commits only fix the cases where we compile the code generically, and have
specific runtime code paths. However, when compiling for a native target the
compiler will freely use AVX instructions when it feels it will lead to faster
code. There is no run-time checking we can do to avoid this, hence the need
for changing the build-time configuration.

/Bruce

quoted

Regards,
Pablo

quoted

quoted

Compile flag

defconfig_x86_64-default-linuxapp-gcc



Dpdk version

PACKAGE_VERSION_MAJOR_NUMBER=1

PACKAGE_VERSION_MINOR_NUMBER=6

PACKAGE_VERSION_PATCH_NUMBER=0

PACKAGE_VERSION_BUILD_NUMBER=18



Gcc version

gcc (GCC) 4.4.6 20120305 (Red Hat 4.4.6-4)



OS

CentOS release 6.3 (Final)

On Wed, Nov 12, 2014 at 04:16:12PM +0000, Bruce Richardson wrote:

On Wed, Nov 12, 2014 at 10:23:49AM -0500, Neil Horman wrote:

quoted

On Wed, Nov 12, 2014 at 02:24:10PM +0000, De Lara Guarch, Pablo wrote:

quoted

quoted

-----Original Message-----
From: dev [mailto:dev-bounces-VfR2kkLFssw@public.gmane.org] On Behalf Of Masaru Oki
Sent: Wednesday, November 12, 2014 1:48 PM
To: Yaron Illouz
Cc: <redacted>
Subject: Re: [dpdk-dev] compile dpdk with no avx

Hi,

Some libraries need AVX instruction, but if you don't use, it can disable.
  e.g. CONFIG_RTE_LIBRTE_IXGBE_PMD=n in config file.


2014-11-12 21:45 GMT+09:00 Yaron Illouz [off-list ref]:

quoted

Hi



I use dpdk in my product. I can't change my dpdk version.

I compile it on a server that have avx.

Most of the time, it run on machine that have avx, but not always.



When running the product on a machine with no avx, it crash on illegal
instruction.

The current solution is to build it on a computer with no avx.



Is there a compilation flag to disable avx? So it doesn't matter on
which computer I compiled it.

Basically, you are looking at cross-compiling DPDK. One thing you could do
 is go to one of the config files (i.e. defconfig_x86-64-native-linuxapp-gcc) 
and change CONFIG_RTE_MACHINE, from "native" to one of the
 micro-architectures that do not have avx, such as "wsm" (Westmere).

What version of dpdk are you running?  We fixed this a while ago with
commits 8777aabc538fdac24457958eaab929f33d6c4cdf and
074f54ad03ee0c84dcae235933e2b426208fe591.  They do runtime checking for
availability of the AVX and SSE3 instructions and only exeucte paths using those
instructions if the running cpu supports them.  Note that you are still required
to build for the default arch.
Neil

Hi Neil,

those commits only fix the cases where we compile the code generically, and have
specific runtime code paths. However, when compiling for a native target the
compiler will freely use AVX instructions when it feels it will lead to faster
code. There is no run-time checking we can do to avoid this, hence the need
for changing the build-time configuration.

Yes, please see the last sentence in my post.
Neil

/Bruce

quoted

quoted

Regards,
Pablo

quoted

quoted

Compile flag

defconfig_x86_64-default-linuxapp-gcc



Dpdk version

PACKAGE_VERSION_MAJOR_NUMBER=1

PACKAGE_VERSION_MINOR_NUMBER=6

PACKAGE_VERSION_PATCH_NUMBER=0

PACKAGE_VERSION_BUILD_NUMBER=18



Gcc version

gcc (GCC) 4.4.6 20120305 (Red Hat 4.4.6-4)



OS

CentOS release 6.3 (Final)