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From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Dongsheng Yang <dongsheng.yang@easystack.cn>
Cc: starvik@axis.com, jesper.nilsson@axis.com,
	Dongsheng Yang <yangds.fnst@cn.fujitsu.com>,
	shengyong1@huawei.com, linux-cris-kernel@axis.com,
	dedekind1@gmail.com, Brian Norris <computersforpeace@gmail.com>,
	Richard Weinberger <richard@nod.at>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	dooooongsheng.yang@gmail.com, jschultz@xes-inc.com,
	fabf@skynet.be, mtownsend1973@gmail.com,
	linux-mtd@lists.infradead.org,
	Colin King <colin.king@canonical.com>,
	asierra@xes-inc.com, dmitry.torokhov@gmail.com,
	Dongsheng Yang <dongsheng081251@gmail.com>,
	David Woodhouse <dwmw2@infradead.org>
Subject: Re: MTD RAID
Date: Mon, 22 Aug 2016 09:09:47 +0200	[thread overview]
Message-ID: <20160822090947.01ff9dab@bbrezillon> (raw)
In-Reply-To: <57BA7924.506@easystack.cn>

On Mon, 22 Aug 2016 12:01:40 +0800
Dongsheng Yang <dongsheng.yang@easystack.cn> wrote:

> On 08/19/2016 07:55 PM, Boris Brezillon wrote:
> > On Fri, 19 Aug 2016 19:20:40 +0800 (GMT+08:00)
> > 杨东升 <dongsheng.yang@easystack.cn> wrote:
> >  
> >> Hi guys,Sorry I think i did not express myself clearly. From this reference:
> >>
> >>
> >> https://linas.org/linux/Software-RAID/Software-RAID.txt
> >>
> >>
> >> we can see, RAID stands for "Redundant Array of Inexpensive Disks"
> >> and is meant to be a way of creating a fast and reliable
> >> disk-drive subsystem out of individual disks. In the PC
> >> world, "I" has come to stand for "Independent".
> >>
> >>
> >> There are two benifets in RAID, "fast" and "reliable".
> >> So I　introduce the RAID framework in MTD world. and implement
> >> 3 types of RAID currently.
> >>
> >>
> >> (1) single: I reuse this work same with what it is in BTRFS.
> >> It's not a standard RAID level. But just concat the devices.
> >>
> >>
> >> (2) RAID0: also known as Striping mode. This can make device faster.
> >>  From what I show in my first email, we can see we can get 51.1 MB/s in dd
> >> although the original device is only 14.0 MB/s.  
> > Some comments on your results. It's all theoretical (based on nandsim),
> > and assuming your NAND chips are connected to the same NAND controller
> > you would just get the same perf as in 'single' mode (accesses through
> > the NAND controller are currently serialized, that's something I'm
> > trying to change but it's not here yet).
> >
> > So yes, in an ideal word, sequential accesses would be improved, but
> > we're not here yet. BTW, did you run this test on a real HW?  
> 
> http://www.fujitsu.com/global/about/resources/news/press-releases/2015/1119-01.html

Is this solution really using a mainline kernel?

  reply	other threads:[~2016-08-22  7:10 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CA+qeAOpuZ0CXZP8tCWdhoVvTEKAw26gtz63-UJmQ4XLSXAd=Yg@mail.gmail.com>
2016-08-19  6:49 ` MTD RAID Boris Brezillon
2016-08-19  7:08   ` Dongsheng Yang
2016-08-19  7:15     ` Dongsheng Yang
2016-08-19  7:28       ` Dongsheng Yang
2016-08-19  8:20     ` Boris Brezillon
     [not found]       ` <CA+qeAOrSAi9uTHGCi-5cAJpM_O45oJUihNP-rHHa1FWL7_ZKHQ@mail.gmail.com>
2016-08-19  9:37         ` Boris Brezillon
2016-08-19 10:22           ` Dongsheng Yang
2016-08-19 11:36             ` Boris Brezillon
     [not found]       ` <57B6CC7B.1060208@easystack.cn>
2016-08-19  9:47         ` Richard Weinberger
2016-08-19 10:30           ` Dongsheng Yang
2016-08-19 10:30           ` Artem Bityutskiy
2016-08-19 10:38             ` Dongsheng Yang
     [not found]               ` <AL*AZwAyAecQSM1UjjjNxao0.3.1471605640762.Hmail.dongsheng.yang@easystack.cn>
2016-08-19 11:55                 ` Boris Brezillon
2016-08-22  4:01                   ` Dongsheng Yang
2016-08-22  7:09                     ` Boris Brezillon [this message]
     [not found]                   ` <57BA6FFA.6000601@easystack.cn>
2016-08-22  7:07                     ` Boris Brezillon
2016-08-22  7:27                     ` Artem Bityutskiy
     [not found]                       ` <CAAp9bSh-geStbHpA6+vYdLfNLcinWkfVLOGmX4kdRbja+d2MdA@mail.gmail.com>
2016-08-22 14:54                         ` Artem Bityutskiy
2016-08-22 15:30                           ` David Woodhouse
2016-08-23  3:44   ` Dongsheng Yang

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