From: Jason Gunthorpe <jgg@ziepe.ca>
To: "Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>
Cc: "Wangzhou (B)" <wangzhou1@hisilicon.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Arnd Bergmann <arnd@arndb.de>,
Zhangfei Gao <zhangfei.gao@linaro.org>,
"linux-accelerators@lists.ozlabs.org"
<linux-accelerators@lists.ozlabs.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"Liguozhu (Kenneth)" <liguozhu@hisilicon.com>,
"chensihang (A)" <chensihang1@hisilicon.com>
Subject: Re: [RFC PATCH v2] uacce: Add uacce_ctrl misc device
Date: Mon, 25 Jan 2021 21:13:04 -0400 [thread overview]
Message-ID: <20210126011304.GZ4605@ziepe.ca> (raw)
In-Reply-To: <5f64a68042c64f37b5cba74028bd2189@hisilicon.com>
On Mon, Jan 25, 2021 at 11:35:22PM +0000, Song Bao Hua (Barry Song) wrote:
> > On Mon, Jan 25, 2021 at 10:21:14PM +0000, Song Bao Hua (Barry Song) wrote:
> > > mlock, while certainly be able to prevent swapping out, it won't
> > > be able to stop page moving due to:
> > > * memory compaction in alloc_pages()
> > > * making huge pages
> > > * numa balance
> > > * memory compaction in CMA
> >
> > Enabling those things is a major reason to have SVA device in the
> > first place, providing a SW API to turn it all off seems like the
> > wrong direction.
>
> I wouldn't say this is a major reason to have SVA. If we read the
> history of SVA and papers, people would think easy programming due
> to data struct sharing between cpu and device, and process space
> isolation in device would be the major reasons for SVA. SVA also
> declares it supports zero-copy while zero-copy doesn't necessarily
> depend on SVA.
Once you have to explicitly make system calls to declare memory under
IO, you loose all of that.
Since you've asked the app to be explicit about the DMAs it intends to
do, there is not really much reason to use SVA for those DMAs anymore.
Jason
next prev parent reply other threads:[~2021-01-26 1:13 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-25 8:34 [RFC PATCH v2] uacce: Add uacce_ctrl misc device Zhou Wang
2021-01-25 9:28 ` Greg Kroah-Hartman
2021-01-25 12:47 ` Zhou Wang
2021-01-25 15:47 ` Jason Gunthorpe
2021-01-25 22:21 ` Song Bao Hua (Barry Song)
2021-01-25 23:16 ` Jason Gunthorpe
2021-01-25 23:35 ` Song Bao Hua (Barry Song)
2021-01-26 1:13 ` Jason Gunthorpe [this message]
2021-01-26 1:26 ` Song Bao Hua (Barry Song)
2021-01-26 18:20 ` Jason Gunthorpe
2021-01-28 1:28 ` Song Bao Hua (Barry Song)
2021-01-29 10:09 ` Tian, Kevin
2021-01-29 10:33 ` Song Bao Hua (Barry Song)
2021-02-01 23:44 ` Jason Gunthorpe
2021-02-02 0:22 ` Song Bao Hua (Barry Song)
2021-02-02 2:51 ` Tian, Kevin
2021-02-02 3:47 ` Song Bao Hua (Barry Song)
2021-01-26 9:00 ` Zhou Wang
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