Hi Pai,
I have been trying to disable avx512 in OVS for the platform which
doesn't support avx512.
Building fails and it seems that it is not disabled. Any idea about it?
# ./configure --with-dpdk=yes --prefix=/usr --localstatedir=/var
--sysconfdir=/etc CFLAGS="-mno-avx512f"
# make
libtool: compile: gcc -DHAVE_CONFIG_H -I. -I ./include -I ./include
-I ./lib -I ./lib -Wstrict-prototypes -Wall -Wextra -Wno-sign-compare
-Wpointer-arith -Wformat -Wformat-security -Wswitch-enum
-Wunused-parameter -Wbad-function-cast -Wcast-align
-Wstrict-prototypes -Wold-style-definition -Wmissing-prototypes
-Wmissing-field-initializers -fno-strict-aliasing -Wswitch-bool
-Wlogical-not-parentheses -Wsizeof-array-argument -Wbool-compare
-Wshift-negative-value -Wduplicated-cond -Wshadow -mssse3 -include
rte_config.h -DOPENSSL_LOAD_CONF -I/usr/local/include
-D_FILE_OFFSET_BITS=64 -mno-avx512f -DHAVE_AVX512F
-DHAVE_LD_AVX512_GOOD -MT lib/netdev-dpdk.lo -MD -MP -MF
lib/.deps/netdev-dpdk.Tpo -c lib/netdev-dpdk.c -o lib/netdev-dpdk.o
In file included from
/usr/lib64/gcc/x86_64-suse-linux/7/include/immintrin.h:41:0,
from /usr/lib64/gcc/x86_64-suse-linux/7/include/x86intrin.h:48,
from /usr/local/include/rte_vect.h:28,
from /usr/local/include/rte_memcpy.h:17,
from /usr/local/include/rte_ether.h:21,
from /usr/local/include/rte_ethdev.h:159,
from lib/netdev-dpdk.c:39:
/usr/local/include/rte_memcpy.h: In function βrte_mov32β:
/usr/lib64/gcc/x86_64-suse-linux/7/include/avxintrin.h:926:1: error:
inlining failed in call to always_inline β_mm256_storeu_si256β: target
specific option mismatch
_mm256_storeu_si256 (__m256i_u *__P, __m256i __A)
^~~~~~~~~~~~~~~~~~~
In file included from /usr/local/include/rte_ether.h:21:0,
from /usr/local/include/rte_ethdev.h:159,
from lib/netdev-dpdk.c:39:
/usr/local/include/rte_memcpy.h:320:2: note: called from here
_mm256_storeu_si256((__m256i *)dst, ymm0);
On Thu, Jun 2, 2022 at 4:00 PM Pai G, Sunil <sunil.pa...@intel.com> wrote:
>
> Hi Li,
>
> The assumption of ovs being dependent on dpdk for avx512 might not be true.
> I found these two commits below in ovs-2.14.2 which strips out the "-march"
> and "-mno-avx512f" flags exported by dpdk i.e removes dependency on DPDK. The
> reason for this is rightly mentioned below as well. Hope this helps.
>
>
> commit bb8f0e2a810889241f1d886d160ccee9b96c4d63
> Author: Ian Stokes <ian.sto...@intel.com>
> Date: Fri Jan 15 15:46:02 2021 +0000
>
> acinclude: Strip out -mno-avx512f provided by DPDK.
>
> DPDK forces '-mno-avx512f' flag for the application if the toolchain
> used to build DPDK had broken AVX512 support.
>
> DPDK forces '-mno-avx512f' flag for the application if the toolchain
> used to build DPDK had broken AVX512 support. But OVS could be built
> with a completely different or fixed toolchain with correct avx512
> support.
>
> Fix that by stripping out `-mno-avx512f` as we already do for '-march'.
> This will allow the OVS to decide if the AVX512 can be used.
>
> Reordering of CFLAGS (i.e. adding DPDK flags before OVS ones) is not an
> option since autotools might reorder them back later and it's very
> unpredictable.
>
> Reported-at: https://github.com/openvswitch/ovs-issues/issues/201
> Signed-off-by: Ilya Maximets <i.maxim...@ovn.org>
> Co-authored-by: Ilya Maximets <i.maxim...@ovn.org>
> Signed-off-by: Ian Stokes <ian.sto...@intel.com>
>
> commit e9f9104d00006a83ce7efd702120171835991779
> Author: Ian Stokes <ian.sto...@intel.com>
> Date: Fri Jan 15 14:54:04 2021 +0000
>
> acinclude: Strip out -march provided by DPDK.
>
> DPDK flags may include -march. Forcing -march could be
> considered too heavy a requirement when users compile OVS from
> source and could override user provided options.
>
> Resolve this by stripping -march from provided DPDK flags.
>
> Signed-off-by: Ian Stokes <ian.sto...@intel.com>
>
>
>
> Thanks and Regards,
> Sunil
>
> > -----Original Message-----
> > From: discuss <ovs-discuss-boun...@openvswitch.org> On Behalf Of Li Zhang
> > Sent: Thursday, June 2, 2022 6:35 PM
> > To: ovs-discuss@openvswitch.org
> > Subject: [ovs-discuss] One question about AVX512 support
> >
> > Hi all,
> >
> > We are using openvswitch 2.14.2, and dpdk-19.11.4. I found avx512 is
> > enabled by default but it's disabled in DPDK. But I think ovs is dependent
> > on the dpdk library, right? But why does ovs work with
> > avx512 disabled in DPDK?
> >
> > I am not quite sure about the relationship between OVS and DPDK, any
> > suggestions?
> >
> > --
> >
> > Best Regards
> > -Li
> > _______________________________________________
> > discuss mailing list
> > disc...@openvswitch.org
> > https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
--
Best Regards
-Li
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