From: Sinan Kaya <okaya@codeaurora.org>
To: Alexander Duyck <alexander.duyck@gmail.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Arnd Bergmann <arnd@arndb.de>, Jason Gunthorpe <jgg@ziepe.ca>,
David Laight <David.Laight@aculab.com>, Oliver <oohall@gmail.com>,
"open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)"
<linuxppc-dev@lists.ozlabs.org>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
Will Deacon <will.deacon@arm.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: RFC on writel and writel_relaxed
Date: Tue, 27 Mar 2018 18:35:34 -0400 [thread overview]
Message-ID: <afcdcbdb-5caa-6ea3-d3ed-d26237f0968f@codeaurora.org> (raw)
In-Reply-To: <CAKgT0UfZKBTYPCqWtBF=N5TPFrbsv0ZU+2GHMqF3J4BM9Hw4yw@mail.gmail.com>
On 3/27/2018 5:54 PM, Alexander Duyck wrote:
> I view the wmb() + writel_relaxed() as more of a driver owning and
> handling this itself. Besides in the Intel Ethernet driver case it is
> better performance as our wmb() placement for us also provides a
> secondary barrier so we don't need to add a separate smp_wmb() to deal
> with a potential race we have with the Tx cleanup.
Thanks for the reminder.
I forgot about the double barrier optimization. wmb() + writel_relaxed()
seems to be the best option for Intel network drivers at this moment.
Otherwise, we'll have to remove wmb() and throw in smp barriers there
like you mentioned.
I'll leave the changes in the Intel drivers alone.
--
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
next prev parent reply other threads:[~2018-03-27 22:35 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-27 21:54 RFC on writel and writel_relaxed Alexander Duyck
2018-03-27 22:35 ` Sinan Kaya [this message]
2018-03-27 23:43 ` Benjamin Herrenschmidt
[not found] <1521692689.16434.293.camel@kernel.crashing.org>
[not found] ` <CAOSf1CFv1HHCL3YOVhRn2U=grdNjaQ=A4m3xwxN2Rek1-_TySg@mail.gmail.com>
[not found] ` <1521726722.16434.312.camel@kernel.crashing.org>
[not found] ` <20180323163510.GC13033@ziepe.ca>
[not found] ` <1521854626.16434.359.camel@kernel.crashing.org>
[not found] ` <58ce5b83f40f4775bec1be8db66adb0d@AcuMS.aculab.com>
[not found] ` <20180326165425.GA15554@ziepe.ca>
[not found] ` <CAK8P3a1zeMyj+Z-y4ER4moY6Zip9EWNOinf+VnboGOrgiwbBZA@mail.gmail.com>
[not found] ` <20180326202545.GB15554@ziepe.ca>
[not found] ` <CAK8P3a3fc43ZcW626hmsd3DVcLw7hGkdUMxp7s4Rn3mdkziwMQ@mail.gmail.com>
[not found] ` <20180326210951.GD15554@ziepe.ca>
[not found] ` <CAK8P3a2UU1xAM0NLo7Q4-Xgo1SzY3De1uqpFudr+2ZW7nHEPmA@mail.gmail.com>
[not found] ` <1522101616.7364.13.camel@kernel.crashing.org>
2018-03-27 14:46 ` Sinan Kaya
2018-03-27 15:01 ` Jose Abreu
2018-03-27 15:10 ` Will Deacon
2018-03-27 18:54 ` Alexander Duyck
2018-03-27 19:54 ` Arnd Bergmann
2018-03-27 20:46 ` Arnd Bergmann
2018-03-27 21:33 ` Benjamin Herrenschmidt
2018-03-28 0:39 ` Linus Torvalds
2018-03-28 1:03 ` Benjamin Herrenschmidt
2018-03-28 2:51 ` Linus Torvalds
2018-03-28 3:24 ` Sinan Kaya
2018-03-28 4:41 ` Benjamin Herrenschmidt
2018-03-28 6:14 ` Linus Torvalds
2018-03-28 11:41 ` okaya
2018-03-28 15:13 ` Benjamin Herrenschmidt
2018-03-28 15:55 ` David Miller
2018-03-28 16:23 ` Nicholas Piggin
2018-03-28 21:31 ` Benjamin Herrenschmidt
2018-03-28 22:09 ` Nicholas Piggin
2018-03-29 9:20 ` Will Deacon
2018-03-29 13:56 ` Sinan Kaya
2018-03-29 14:04 ` David Miller
2018-03-29 16:29 ` Arnd Bergmann
2018-03-29 16:59 ` Sinan Kaya
2018-03-30 1:40 ` Benjamin Herrenschmidt
2018-04-02 13:01 ` Sinan Kaya
2018-03-28 4:33 ` Benjamin Herrenschmidt
2018-03-28 6:26 ` Linus Torvalds
2018-03-28 6:42 ` Benjamin Herrenschmidt
2018-03-28 6:53 ` Linus Torvalds
2018-03-28 6:56 ` Benjamin Herrenschmidt
2018-03-28 7:11 ` Arnd Bergmann
2018-03-28 7:42 ` Benjamin Herrenschmidt
2018-03-28 9:07 ` Will Deacon
2018-03-28 9:56 ` Benjamin Herrenschmidt
2018-03-28 11:30 ` David Laight
2018-03-28 15:12 ` Benjamin Herrenschmidt
2018-03-28 16:16 ` David Laight
2018-03-28 1:21 ` Benjamin Herrenschmidt
2018-03-27 21:35 ` Benjamin Herrenschmidt
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