From: "hch@lst.de" <hch@lst.de>
To: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
Cc: "hch@infradead.org" <hch@infradead.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
"sagi@grimberg.me" <sagi@grimberg.me>, "hch@lst.de" <hch@lst.de>,
Damien Le Moal <Damien.LeMoal@wdc.com>,
Johannes Thumshirn <Johannes.Thumshirn@wdc.com>
Subject: Re: [PATCH V4 1/9] block: allow bvec for zone append get pages
Date: Fri, 4 Dec 2020 09:46:34 +0100 [thread overview]
Message-ID: <20201204084634.GA5845@lst.de> (raw)
In-Reply-To: <BYAPR04MB49652F70D16357D420E616AE86F10@BYAPR04MB4965.namprd04.prod.outlook.com>
On Fri, Dec 04, 2020 at 02:43:10AM +0000, Chaitanya Kulkarni wrote:
> >> Remove the bvec check in the bio_iov_iter_get_pages() for
> >> REQ_OP_ZONE_APPEND so that we can reuse the code and build iter from
> >> bvec.
> > We should do the same optimization for bvec pages that the normal path
> > does. That being said using bio_iov_iter_get_pages in nvmet does not
> > make any sense to me whatsover.
> >
> Are you referring to the inline bvec ? then yes, I'll add it in next
> version.
>
> I did not understand bio_iov_iter_get_pages() comment though.
>
> Reimplementing the bio loop over sg with the use of bio_add_hw_page() seems
>
> repetition of the code which we already have in bio_iov_iter_get_pages().
>
>
> Can you please explain why bio_iov_iter_get_pages() not the right way ?
bio_iov_iter_get_pages is highly inefficient for this use case, as we'll
need to allocate two sets of bio_vecs. It also is rather redundant as
Zone Append should be able to just largely reuse the write path.
next prev parent reply other threads:[~2020-12-04 8:47 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-02 6:22 [PATCH V4 0/9] nvmet: add ZBD backend support Chaitanya Kulkarni
2020-12-02 6:22 ` [PATCH V4 1/9] block: allow bvec for zone append get pages Chaitanya Kulkarni
2020-12-02 8:34 ` Johannes Thumshirn
2020-12-02 8:55 ` Christoph Hellwig
2020-12-04 2:43 ` Chaitanya Kulkarni
2020-12-04 8:46 ` hch [this message]
2020-12-02 6:22 ` [PATCH V4 2/9] nvmet: add ZNS support for bdev-ns Chaitanya Kulkarni
2020-12-02 9:07 ` Christoph Hellwig
2020-12-04 3:13 ` Chaitanya Kulkarni
2020-12-04 9:27 ` Christoph Hellwig
2020-12-02 6:22 ` [PATCH V4 3/9] nvmet: trim down id-desclist to use req->ns Chaitanya Kulkarni
2020-12-02 9:08 ` Christoph Hellwig
2020-12-04 3:14 ` Chaitanya Kulkarni
2020-12-02 6:22 ` [PATCH V4 4/9] nvmet: add NVME_CSI_ZNS in ns-desc for zbdev Chaitanya Kulkarni
2020-12-02 9:09 ` Christoph Hellwig
2020-12-04 3:14 ` Chaitanya Kulkarni
2020-12-02 6:22 ` [PATCH V4 5/9] nvmet: add cns-cs-ctrl in id-ctrl for ZNS bdev Chaitanya Kulkarni
2020-12-02 9:10 ` Christoph Hellwig
2020-12-04 3:20 ` Chaitanya Kulkarni
2020-12-04 9:28 ` Christoph Hellwig
2020-12-02 6:22 ` [PATCH V4 6/9] nvmet: add cns-cs-ns " Chaitanya Kulkarni
2020-12-02 6:22 ` [PATCH V4 7/9] nvmet: add zns cmd effects to support zbdev Chaitanya Kulkarni
2020-12-02 6:22 ` [PATCH V4 8/9] nvmet: add zns bdev config support Chaitanya Kulkarni
2020-12-02 6:22 ` [PATCH V4 9/9] nvmet: add ZNS based I/O cmds handlers Chaitanya Kulkarni
2020-12-02 9:20 ` [PATCH V4 0/9] nvmet: add ZBD backend support Christoph Hellwig
2020-12-10 3:07 ` Chaitanya Kulkarni
2020-12-10 15:15 ` Keith Busch
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