From: jgg@ziepe.ca (Jason Gunthorpe)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v4 4/6] infiniband: cxgb4: Eliminate duplicate barriers on weakly-ordered archs
Date: Thu, 22 Mar 2018 15:25:10 -0600 [thread overview]
Message-ID: <20180322212510.GE9469@ziepe.ca> (raw)
In-Reply-To: <BY2PR1201MB098367F8F217A8BF66AE68B6C8A90@BY2PR1201MB0983.namprd12.prod.outlook.com>
On Thu, Mar 22, 2018 at 08:45:11PM +0000, Casey Leedom wrote:
> I'm guessing~ that this line in the documentation ~may~ imply the GCC
> ordering:
>
> ... Note that relaxed accesses to
> the same peripheral are guaranteed to be ordered with respect to each
> other. ...
An arch can't guarentee "ordered with respect to each other" without
preventing the compiler from re-ordering, so yes, any correct
implementation of writel_relaxed must prevent compiler re-ordering.
eg with volatile or a compiler barrier, or whatever.
> In any case, we really only have a few places where we (the various Chelsio
> drivers) need to worry about this: the "Fast Paths" where we have a lot of
> I/O to the device. I think we should leave everything else alone.
Yes.
Jason
next prev parent reply other threads:[~2018-03-22 21:25 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-20 2:47 [PATCH v4 0/6] ib: Eliminate duplicate barriers on weakly-ordered archs Sinan Kaya
2018-03-20 2:47 ` [PATCH v4 1/6] RDMA/bnxt_re: " Sinan Kaya
2018-03-20 14:48 ` Jason Gunthorpe
2018-03-20 15:00 ` Sinan Kaya
2018-03-20 15:08 ` Sinan Kaya
2018-03-20 15:23 ` Jason Gunthorpe
2018-03-20 15:20 ` Jason Gunthorpe
2018-03-20 15:30 ` Sinan Kaya
2018-03-20 16:02 ` Jason Gunthorpe
2018-03-20 2:47 ` [PATCH v4 2/6] IB/mlx4: " Sinan Kaya
2018-03-20 14:48 ` Jason Gunthorpe
2018-03-20 2:47 ` [PATCH v4 3/6] RDMA/i40iw: " Sinan Kaya
2018-03-20 14:56 ` Jason Gunthorpe
2018-03-21 13:38 ` Shiraz Saleem
2018-03-21 20:02 ` Jason Gunthorpe
2018-03-21 21:01 ` Sinan Kaya
2018-03-20 2:47 ` [PATCH v4 4/6] infiniband: cxgb4: " Sinan Kaya
2018-03-20 14:51 ` Jason Gunthorpe
2018-03-20 15:10 ` Steve Wise
2018-03-20 15:38 ` Steve Wise
2018-03-22 6:44 ` kbuild test robot
2018-03-22 12:24 ` okaya at codeaurora.org
2018-03-22 12:48 ` okaya at codeaurora.org
2018-03-22 14:33 ` Sinan Kaya
2018-03-22 14:40 ` Steve Wise
2018-03-22 14:52 ` Sinan Kaya
2018-03-22 16:28 ` Steve Wise
2018-03-22 19:44 ` Casey Leedom
2018-03-22 20:16 ` Jason Gunthorpe
2018-03-22 20:45 ` Casey Leedom
2018-03-22 21:25 ` Jason Gunthorpe [this message]
2018-03-22 21:27 ` Sinan Kaya
2018-03-22 22:02 ` Casey Leedom
[not found] ` <437ab002-b8db-24aa-583e-0e61d61aaa97@codeaurora.org>
2018-03-22 18:46 ` Jason Gunthorpe
2018-03-22 18:48 ` Jason Gunthorpe
2018-03-22 18:58 ` Sinan Kaya
2018-03-23 4:14 ` kbuild test robot
2018-03-20 2:47 ` [PATCH v4 5/6] IB/nes: " Sinan Kaya
2018-03-20 14:54 ` Jason Gunthorpe
2018-03-20 15:23 ` Sinan Kaya
2018-03-20 16:01 ` Jason Gunthorpe
2018-03-20 16:08 ` Sinan Kaya
2018-03-20 16:29 ` Jason Gunthorpe
2018-03-20 2:47 ` [PATCH v4 6/6] RDMA/qedr: eliminate duplicate barriers on weakly-ordered archs #2 Sinan Kaya
2018-03-20 7:38 ` Kalderon, Michal
2018-03-20 14:55 ` Jason Gunthorpe
2018-03-21 20:08 ` [PATCH v4 0/6] ib: Eliminate duplicate barriers on weakly-ordered archs 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=20180322212510.GE9469@ziepe.ca \
--to=jgg@ziepe.ca \
--cc=linux-arm-kernel@lists.infradead.org \
/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).