On 5/12/20 4:27 AM, Liu, Yong wrote:
>
>
>> -----Original Message-----
>> From: Maxime Coquelin <maxime.coque...@redhat.com>
>> Sent: Monday, May 11, 2020 10:47 PM
>> To: Liu, Yong <yong....@intel.com>; Ye, Xiaolong <xiaolong...@intel.com>;
>> Yigit, Ferruh <ferruh.yi...@intel.com>; dev@dpdk.org
>> Cc: Maxime Coquelin <maxime.coque...@redhat.com>
>> Subject: [PATCH] net/virtio: fix AVX512 datapath selection
>>
>> The AVX512 packed ring datapath selection was only done
>> at build time, but it should also be checked at runtime
>> that the CPU supports it.
>>
>> This patch add a CPU flags check so that non-vectorized
>> path is selected at runtime if AVX512 is not supported.
>>
>> Fixes: ccb10995c2ad ("net/virtio: add election for vectorized path")
>>
>> Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com>
>> ---
>> drivers/net/virtio/virtio_ethdev.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/net/virtio/virtio_ethdev.c
>> b/drivers/net/virtio/virtio_ethdev.c
>> index 312871cb48..49ccef12c7 100644
>> --- a/drivers/net/virtio/virtio_ethdev.c
>> +++ b/drivers/net/virtio/virtio_ethdev.c
>> @@ -1965,8 +1965,10 @@ eth_virtio_dev_init(struct rte_eth_dev *eth_dev)
>> PMD_DRV_LOG(INFO,
>> "building environment do not support
>> packed ring vectorized");
>> #else
>> - hw->use_vec_rx = 1;
>> - hw->use_vec_tx = 1;
>> + if
>> (rte_cpu_get_flag_enabled(RTE_CPUFLAG_AVX512F)) {
>> + hw->use_vec_rx = 1;
>> + hw->use_vec_tx = 1;
>> + }
>> #endif
>
> Hi Maxime,
> Here is pre-setting for vectorized path selection, virtio_dev_configure will
> do second time check.
> Running environment will be checked in second time check. We can move some
> checks from virtio_dev_configure to here, but is it needed to do that?
>
> BTW, both split ring and packed ring will utilized this setting, it will
> break split vectorized datapath is server not has AVX512F flag.
> And it may cause building issue on those platforms which not defined
> RTE_CPUFLAG_AVX512F.
With a bit more of context, we can see that it only affects packed ring
when CC_AVX512_SUPPORT is set. So it does break neither split ring nor
ARM/PPC:
if (vectorized) {
if (!vtpci_packed_queue(hw)) {
hw->use_vec_rx = 1;
} else {
#if !defined(CC_AVX512_SUPPORT)
PMD_DRV_LOG(INFO,
"building environment do not support packed
ring vectorized");
#else
if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_AVX512F)) {
hw->use_vec_rx = 1;
hw->use_vec_tx = 1;
}
#endif
}
}
> Thanks,
> Marvin
>
>> }
>> }
>> --
>> 2.25.4
>
