Re: [ [PATCH v2] 01/13] virtio: Introduce config RTE_VIRTIO_INC_VECTOR

From: Santosh Shukla <sshukla@mvista.com>
To: Thomas Monjalon <thomas.monjalon@6wind.com>
Cc: dev@dpdk.org
Subject: Re: [ [PATCH v2] 01/13] virtio: Introduce config RTE_VIRTIO_INC_VECTOR
Date: Thu, 17 Dec 2015 17:48:48 +0530	[thread overview]
Message-ID: <CAAyOgsbBf94cFyu3Zny-f_HLfWt6z5wOPfMQxsy1wmyG-Qx05w@mail.gmail.com> (raw)
In-Reply-To: <2955349.3QHN8DHquR@xps13>

On Thu, Dec 17, 2015 at 5:33 PM, Thomas Monjalon
<thomas.monjalon@6wind.com> wrote:
> 2015-12-17 17:32, Santosh Shukla:
>> On Mon, Dec 14, 2015 at 6:30 PM, Santosh Shukla <sshukla@mvista.com> wrote:
>> > virtio_recv_pkts_vec and other virtio vector friend apis are written for sse/avx
>> > instructions. For arm64 in particular, virtio vector implementation does not
>> > exist(todo).
>> >
>> > So virtio pmd driver wont build for targets like i686, arm64.  By making
>> > RTE_VIRTIO_INC_VECTOR=n, Driver can build for non-sse/avx targets and will work
>> > in non-vectored virtio mode.
>> >
>> > Signed-off-by: Santosh Shukla <sshukla@mvista.com>
>> > ---
>>
>> Ping?
>>
>> any review  / comment on this patch much appreciated. Thanks
>
> Why not check for SSE/AVX support instead of adding yet another config option?

Ok, keeping a check for sse/avx across the patch wont stand true for
future virtio vectored implementation lets say for arm/arm64 cases
i.e.. sse2neon types. That implies user suppose to keep on appending /
adding checks for see2neon for example and so forth.

On other hand, motivation of including INC_VEC config was inspired
from IXGBE and other pmd drivers who support vectored sse/avx _rx path
and also could work w/o vectored mode. Current virtio is missing such
support and arm dont have vectored sse2neon types implementation right
now so its a blocker for arm case. Also keeping virtio pmd driver
flexible enough to work in non-vectored mode is a requirement/ a
feature.