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From: Jason Gunthorpe <jgg@ziepe.ca>
To: "Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>
Cc: David Hildenbrand <david@redhat.com>,
	"Wangzhou (B)" <wangzhou1@hisilicon.com>,
	"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>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-api@vger.kernel.org" <linux-api@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"kevin.tian@intel.com" <kevin.tian@intel.com>,
	"jean-philippe@linaro.org" <jean-philippe@linaro.org>,
	"eric.auger@redhat.com" <eric.auger@redhat.com>,
	"Liguozhu (Kenneth)" <liguozhu@hisilicon.com>,
	"zhangfei.gao@linaro.org" <zhangfei.gao@linaro.org>,
	"chensihang (A)" <chensihang1@hisilicon.com>
Subject: Re: [RFC PATCH v3 1/2] mempinfd: Add new syscall to provide memory pin
Date: Wed, 10 Feb 2021 14:04:05 -0400	[thread overview]
Message-ID: <20210210180405.GP4718@ziepe.ca> (raw)
In-Reply-To: <2527b4ac8df14fa1b427bef65dace719@hisilicon.com>

On Tue, Feb 09, 2021 at 10:22:47PM +0000, Song Bao Hua (Barry Song) wrote:

> The problem is that SVA declares we can use any memory of a process
> to do I/O. And in real scenarios, we are unable to customize most
> applications to make them use the pool. So we are looking for some
> extension generically for applications such as Nginx, Ceph.

But those applications will suffer jitter even if their are using CPU
to do the same work. I fail to see why adding an accelerator suddenly
means the application owner will care about jitter introduced by
migration/etc.

Again in proper SVA it should be quite unlikely to take a fault caused
by something like migration, on the same likelyhood as the CPU. If
things are faulting so much this is a problem then I think it is a
system level problem with doing too much page motion.

Jason


  reply	other threads:[~2021-02-10 18:04 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-07  8:18 [RFC PATCH v3 0/2] mempinfd: Add new syscall to provide memory pin Zhou Wang
2021-02-07  8:18 ` [RFC PATCH v3 1/2] " Zhou Wang
2021-02-07 21:34   ` Matthew Wilcox
2021-02-07 22:24     ` Song Bao Hua (Barry Song)
2021-02-08  1:30       ` Matthew Wilcox
2021-02-08  2:27         ` Song Bao Hua (Barry Song)
2021-02-08  3:46           ` Hillf Danton
2021-02-08  8:21           ` David Hildenbrand
2021-02-08 10:13             ` Song Bao Hua (Barry Song)
2021-02-08 10:37               ` David Hildenbrand
2021-02-08 20:52                 ` Song Bao Hua (Barry Song)
2021-02-08  2:18       ` David Rientjes
2021-02-08  5:34         ` Song Bao Hua (Barry Song)
2021-02-09  9:02     ` Zhou Wang
2021-02-07 21:51   ` Arnd Bergmann
2021-02-09  9:27     ` Zhou Wang
2021-02-07 22:02   ` Andy Lutomirski
2021-02-09  9:17     ` Zhou Wang
2021-02-09  9:37       ` Greg KH
2021-02-09 11:58         ` Zhou Wang
2021-02-09 12:01           ` Greg KH
2021-02-09 12:20             ` Zhou Wang
2021-02-10 18:50               ` Matthew Wilcox
2021-02-08  8:14   ` David Hildenbrand
2021-02-08 18:33     ` Jason Gunthorpe
2021-02-08 20:35       ` Song Bao Hua (Barry Song)
2021-02-08 21:30         ` Jason Gunthorpe
2021-02-09  3:01           ` Song Bao Hua (Barry Song)
2021-02-09 13:53             ` Jason Gunthorpe
2021-02-09 22:22               ` Song Bao Hua (Barry Song)
2021-02-10 18:04                 ` Jason Gunthorpe [this message]
2021-02-10 21:39                   ` Song Bao Hua (Barry Song)
2021-02-11 10:28                     ` David Hildenbrand
2021-02-07  8:18 ` [RFC PATCH v3 2/2] selftests/vm: add mempinfd test Zhou Wang

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