Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20200818052936.10995-1-joshi.k@samsung.com> <CGME20200818053252epcas5p4ee61d64bba5f6a131105e40330984f5e@epcas5p4.samsung.com>
 <20200818052936.10995-2-joshi.k@samsung.com> <20200818071141.GA2544@lst.de>
In-Reply-To: <20200818071141.GA2544@lst.de>
From:   Kanchan Joshi <joshiiitr@gmail.com>
Date:   Wed, 19 Aug 2020 14:56:29 +0530
Message-ID: <CA+1E3rJg0QOX4YgwWJf8Sm=6C-un4TsRX00E31fbFFPT9LYhXg@mail.gmail.com>
Subject: Re: [PATCH 1/2] nvme: set io-scheduler requirement for ZNS
To:     Christoph Hellwig <hch@lst.de>
Cc:     Kanchan Joshi <joshi.k@samsung.com>, Jens Axboe <axboe@kernel.dk>,
        Damien Le Moal <Damien.LeMoal@wdc.com>, sagi@grimberg.me,
        Johannes Thumshirn <johannes.thumshirn@wdc.com>,
        linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
        Keith Busch <kbusch@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, Aug 18, 2020 at 12:46 PM Christoph Hellwig <hch@lst.de> wrote:
>
> On Tue, Aug 18, 2020 at 10:59:35AM +0530, Kanchan Joshi wrote:
> > Set elevator feature ELEVATOR_F_ZBD_SEQ_WRITE required for ZNS.
>
> No, it is not.

Are you saying MQ-Deadline (write-lock) is not needed for writes on ZNS?
I see that null-block zoned and SCSI-ZBC both set this requirement. I
wonder how it became different for NVMe.

-- 
Kanchan