From: Leon Romanovsky <leon@kernel.org>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Doug Ledford <dledford@redhat.com>,
Jason Gunthorpe <jgg@mellanox.com>,
Christoph Hellwig <hch@infradead.org>,
RDMA mailing list <linux-rdma@vger.kernel.org>,
Or Gerlitz <ogerlitz@mellanox.com>,
Yamin Friedman <yaminf@mellanox.com>,
Saeed Mahameed <saeedm@mellanox.com>,
linux-netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH rdma-next v2 2/3] RDMA/rw: Support threshold for registration vs scattering to local pages
Date: Tue, 8 Oct 2019 08:53:17 +0300 [thread overview]
Message-ID: <20191008055317.GD5855@unreal> (raw)
In-Reply-To: <8d610a58-abb5-941a-2a52-96ab9287572b@acm.org>
On Mon, Oct 07, 2019 at 03:22:30PM -0700, Bart Van Assche wrote:
> On 10/7/19 9:03 AM, Leon Romanovsky wrote:
> > On Mon, Oct 07, 2019 at 08:07:55AM -0700, Bart Van Assche wrote:
> > > On 10/7/19 6:59 AM, Leon Romanovsky wrote:
> > > > /*
> > > > - * Check if the device might use memory registration. This is currently only
> > > > - * true for iWarp devices. In the future we can hopefully fine tune this based
> > > > - * on HCA driver input.
> > > > + * Check if the device might use memory registration. This is currently
> > > > + * true for iWarp devices and devices that have optimized SGL registration
> > > > + * logic.
> > > > */
> > >
> > > The following sentence in the above comment looks confusing to me: "Check if
> > > the device might use memory registration." That sentence suggests that the
> > > HCA decides whether or not to use memory registration. Isn't it the RDMA R/W
> > > code that decides whether or not to use memory registration?
> >
> > I'm open for any reasonable text, what do you expect to be written there?
>
> Hi Leon,
>
> How about the following (not sure whether this is correct)?
>
> /*
> * Report whether memory registration should be used. Memory
> * registration must be used for iWarp devices because of
> * iWARP-specific limitations. Memory registration is also enabled if
> * registering memory will yield better performance than using multiple
> * SGE entries.
> */
"Better performance" is relevant for mlx5 only, maybe others will use
this max_.. field to overcome their HW limitations.
Thanks
>
> Thanks,
>
> Bart.
next prev parent reply other threads:[~2019-10-08 5:53 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-07 13:59 [PATCH rdma-next v2 0/3] Optimize SGL registration Leon Romanovsky
2019-10-07 13:59 ` [PATCH mlx5-next v2 1/3] net/mlx5: Expose optimal performance scatter entries capability Leon Romanovsky
2019-10-07 15:02 ` Bart Van Assche
2019-10-07 15:54 ` Leon Romanovsky
2019-10-08 5:55 ` Leon Romanovsky
2019-10-07 13:59 ` [PATCH rdma-next v2 2/3] RDMA/rw: Support threshold for registration vs scattering to local pages Leon Romanovsky
2019-10-07 15:00 ` Christoph Hellwig
2019-10-07 15:57 ` Leon Romanovsky
2019-10-07 15:07 ` Bart Van Assche
2019-10-07 16:03 ` Leon Romanovsky
2019-10-07 22:22 ` Bart Van Assche
2019-10-08 5:53 ` Leon Romanovsky [this message]
2019-10-07 15:12 ` Bart Van Assche
2019-10-07 15:58 ` Leon Romanovsky
2019-10-07 13:59 ` [PATCH rdma-next v2 3/3] RDMA/mlx5: Add capability for max sge to get optimized performance Leon Romanovsky
2019-10-15 8:15 ` [PATCH rdma-next v2 0/3] Optimize SGL registration Leon Romanovsky
2019-10-22 17:42 ` Jason Gunthorpe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191008055317.GD5855@unreal \
--to=leon@kernel.org \
--cc=bvanassche@acm.org \
--cc=dledford@redhat.com \
--cc=hch@infradead.org \
--cc=jgg@mellanox.com \
--cc=linux-rdma@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=ogerlitz@mellanox.com \
--cc=saeedm@mellanox.com \
--cc=yaminf@mellanox.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).