From: "yangx.jy@fujitsu.com" <yangx.jy@fujitsu.com>
To: Jason Gunthorpe <jgg@nvidia.com>, Tom Talpey <tom@talpey.com>
Cc: "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
"yanjun.zhu@linux.dev" <yanjun.zhu@linux.dev>,
"rpearsonhpe@gmail.com" <rpearsonhpe@gmail.com>,
"y-goto@fujitsu.com" <y-goto@fujitsu.com>,
"lizhijian@fujitsu.com" <lizhijian@fujitsu.com>,
"tomasz.gromadzki@intel.com" <tomasz.gromadzki@intel.com>
Subject: Re: [RFC PATCH 2/2] RDMA/rxe: Add RDMA Atomic Write operation
Date: Thu, 6 Jan 2022 10:52:47 +0000 [thread overview]
Message-ID: <61D6C9F9.10808@fujitsu.com> (raw)
In-Reply-To: <20220105235354.GV2328285@nvidia.com>
On 2022/1/6 7:53, Jason Gunthorpe wrote:
> On Thu, Dec 30, 2021 at 04:39:01PM -0500, Tom Talpey wrote:
>
>> Because RXE is a software provider, I believe the most natural approach
>> here is to use an atomic64_set(dst, *src).
> A smp_store_release() is most likely sufficient.
Hi Jason, Tom
Is smp_store_mb() better here? It calls WRITE_ONCE + smb_mb/barrier().
I think the semantics of 'atomic write' is to do atomic write and make
the 8-byte data reach the memory.
Best Regards,
Xiao Yang
> The spec word 'atomic' is pretty confusing. What it is asking for, in
> the modern memory model vernacular, is 'write once' for the entire
> payload and 'release' to only be observable after other stores made by
> the same QP.
>
> 'release' semantics will depend on the CPU complex having a release
> dependency chain throughout all CPUs that completed any prior response
> on the QP. It looks like this is achieved through tasklet scheduling..
>
> Jason
next prev parent reply other threads:[~2022-01-06 10:52 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-30 12:14 [RFC PATCH 0/2] RDMA/rxe: Add RDMA Atomic Write operation Xiao Yang
2021-12-30 12:14 ` [RFC PATCH 1/2] RDMA/rxe: Rename send_atomic_ack() and atomic member of struct resp_res Xiao Yang
2021-12-30 12:14 ` [RFC PATCH 2/2] RDMA/rxe: Add RDMA Atomic Write operation Xiao Yang
2021-12-30 21:39 ` Tom Talpey
2021-12-31 8:29 ` yangx.jy
2021-12-31 15:09 ` Tom Talpey
[not found] ` <61D563B4.2070106@fujitsu.com>
2022-01-07 15:50 ` Tom Talpey
2022-01-07 17:11 ` Jason Gunthorpe
2022-01-12 9:24 ` yangx.jy
2022-01-05 23:53 ` Jason Gunthorpe
2022-01-06 10:52 ` yangx.jy [this message]
2022-01-06 13:00 ` Jason Gunthorpe
2022-01-07 2:15 ` yangx.jy
2022-01-07 12:22 ` Jason Gunthorpe
2022-01-07 15:38 ` Tom Talpey
2022-01-07 19:28 ` Jason Gunthorpe
2022-01-07 20:11 ` Tom Talpey
2021-12-31 3:01 ` lizhijian
2021-12-31 6:02 ` yangx.jy
2021-12-30 19:21 ` [RFC PATCH 0/2] " Gromadzki, Tomasz
2021-12-30 21:42 ` Tom Talpey
2021-12-31 6:30 ` yangx.jy
2022-01-04 9:28 ` yangx.jy
2022-01-04 15:17 ` Tom Talpey
2022-01-05 1:00 ` yangx.jy
2022-01-06 0:01 ` Jason Gunthorpe
2022-01-06 1:54 ` yangx.jy
2022-01-10 15:42 ` Jason Gunthorpe
2022-01-11 2:34 ` yangx.jy
2022-01-11 23:29 ` Jason Gunthorpe
2022-02-11 13:18 ` Gromadzki, Tomasz
2022-02-17 3:50 ` yangx.jy
2022-02-19 10:37 ` Leon Romanovsky
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