netdev - Re: [PATCH v1 net-next 05/15] nvme-tcp: Add DDP offload control path

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Message-ID: <c667ccb0-7444-6892-f647-8971d0b0b461@gmail.com>
Date:   Thu, 17 Dec 2020 20:51:31 +0200
From:   Boris Pismenny <borispismenny@...il.com>
To:     Shai Malin <malin1024@...il.com>,
        Boris Pismenny <borisp@...lanox.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "saeedm@...dia.com" <saeedm@...dia.com>, "hch@....de" <hch@....de>,
        "sagi@...mberg.me" <sagi@...mberg.me>,
        "axboe@...com" <axboe@...com>,
        "kbusch@...nel.org" <kbusch@...nel.org>,
        "viro@...iv.linux.org.uk" <viro@...iv.linux.org.uk>,
        "edumazet@...gle.com" <edumazet@...gle.com>
Cc:     Yoray Zack <yorayz@...lanox.com>,
        "yorayz@...dia.com" <yorayz@...dia.com>,
        "boris.pismenny@...il.com" <boris.pismenny@...il.com>,
        Ben Ben-Ishay <benishay@...lanox.com>,
        "benishay@...dia.com" <benishay@...dia.com>,
        "linux-nvme@...ts.infradead.org" <linux-nvme@...ts.infradead.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Or Gerlitz <ogerlitz@...lanox.com>,
        "ogerlitz@...dia.com" <ogerlitz@...dia.com>,
        Shai Malin <smalin@...vell.com>,
        Ariel Elior <aelior@...vell.com>,
        Michal Kalderon <mkalderon@...vell.com>
Subject: Re: [PATCH v1 net-next 05/15] nvme-tcp: Add DDP offload control path



On 15/12/2020 15:33, Shai Malin wrote:
> On 12/14/2020 08:38, Boris Pismenny wrote:
>> On 10/12/2020 19:15, Shai Malin wrote:
>>> diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c index c0c33320fe65..ef96e4a02bbd 100644
>>> --- a/drivers/nvme/host/tcp.c
>>> +++ b/drivers/nvme/host/tcp.c
>>> @@ -14,6 +14,7 @@
>>>  #include <linux/blk-mq.h>
>>>  #include <crypto/hash.h>
>>>  #include <net/busy_poll.h>
>>> +#include <net/tcp_ddp.h>
>>>
>>>  #include "nvme.h"
>>>  #include "fabrics.h"
>>> @@ -62,6 +63,7 @@ enum nvme_tcp_queue_flags {
>>>       NVME_TCP_Q_ALLOCATED    = 0,
>>>       NVME_TCP_Q_LIVE         = 1,
>>>       NVME_TCP_Q_POLLING      = 2,
>>> +     NVME_TCP_Q_OFFLOADS     = 3,
>>>  };
>>>
>>> The same comment from the previous version - we are concerned that perhaps
>>> the generic term "offload" for both the transport type (for the Marvell work)
>>> and for the DDP and CRC offload queue (for the Mellanox work) may be
>>> misleading and confusing to developers and to users.
>>>
>>> As suggested by Sagi, we can call this NVME_TCP_Q_DDP.
>>>
>>
>> While I don't mind changing the naming here. I wonder  why not call the
>> toe you use TOE and not TCP_OFFLOAD, and then offload is free for this?
> 
> Thanks - please do change the name to NVME_TCP_Q_DDP.
> The Marvell nvme-tcp-offload patch series introducing the offloading of both the
> TCP as well as the NVMe/TCP layer, therefore it's not TOE.
> 

Will do.

>>
>> Moreover, the most common use of offload in the kernel is for partial offloads
>> like this one, and not for full offloads (such as toe).
> 
> Because each vendor might implement a different partial offload I
> suggest naming it
> with the specific technique which is used, as was suggested - NVME_TCP_Q_DDP.
> 


IIUC, if TCP/IP is offloaded entirely then it is called TOE. It doesn't matter
than you offload additional stuff (nvme-tcp)