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From: Yufen Yu <yuyufen@huawei.com>
To: Song Liu <song@kernel.org>
Cc: linux-raid <linux-raid@vger.kernel.org>,
	NeilBrown <neilb@suse.com>,
	Guoqing Jiang <guoqing.jiang@cloud.ionos.com>,
	Coly Li <colyli@suse.de>, Xiao Ni <xni@redhat.com>,
	Hou Tao <houtao1@huawei.com>
Subject: Re: [PATCH v3 00/11] md/raid5: set STRIPE_SIZE as a configurable value
Date: Fri, 29 May 2020 17:32:48 +0800	[thread overview]
Message-ID: <e0947530-003b-5090-70f3-4f6d02219033@huawei.com> (raw)
In-Reply-To: <CAPhsuW7DOdPTWX5MNRJULvojFrCQF9_zNH+_ZwkQs4Qug9CpdQ@mail.gmail.com>



On 2020/5/28 22:28, Song Liu wrote:
> On Thu, May 28, 2020 at 7:10 AM Song Liu <song@kernel.org> wrote:
>>
>> On Wed, May 27, 2020 at 6:20 AM Yufen Yu <yuyufen@huawei.com> wrote:
>>>
>>> Hi, all
>>>
>>>   For now, STRIPE_SIZE is equal to the value of PAGE_SIZE. That means, RAID5 will
>>>   issus echo bio to disk at least 64KB when PAGE_SIZE is 64KB in arm64. However,
>>>   filesystem usually issue bio in the unit of 4KB. Then, RAID5 will waste resource
>>>   of disk bandwidth.
>>>
>>
>> Thanks for the patch set.
>>
>> Since this is a big change, I am planning to process this set after
>> upcoming merge window.
>> Please let me know if you need it urgently.

I agree with your plan.

> 
> I haven't thought about this in detail yet: how about compatibility?
> Say we create an
> array with STRIPE_SIZE of 4kB, does it work well after we upgrade kernel to have
> STRIPE_SIZE of 8kB?

Each time upgrade kernel, we need to reboot system to make it effective.
And, system will allocate new stripe_head and buffers base on the new STRIPE_SIZE.
Then everything will be ok and go on running.

STRIPE_SIZE decides each io size issued to array disk and its buffers size in
stripe_head. But each time restart system, we will allocate new buffer and
stripe_head based on the new STRIPE_SIZE. It is no matter what the value before.
So, I think changing STRIPE_SIZE is not problem for upgrade kernel.

Thanks,
Yufen

  reply	other threads:[~2020-05-29  9:32 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-27 13:19 [PATCH v3 00/11] md/raid5: set STRIPE_SIZE as a configurable value Yufen Yu
2020-05-27 13:19 ` [PATCH v3 01/11] md/raid5: add CONFIG_MD_RAID456_STRIPE_SHIFT to set STRIPE_SIZE Yufen Yu
2020-05-27 13:54   ` Guoqing Jiang
2020-05-27 23:30     ` John Stoffel
2020-05-28  6:17     ` Yufen Yu
2020-05-27 15:16   ` Xiao Ni
2020-05-28  6:29     ` Yufen Yu
2020-05-27 20:21   ` kbuild test robot
2020-05-27 20:21     ` kbuild test robot
2020-05-28 14:23   ` Song Liu
2020-05-29  8:42     ` Yufen Yu
2020-05-27 13:19 ` [PATCH v3 02/11] md/raid5: add a member of r5pages for struct stripe_head Yufen Yu
2020-05-27 13:19 ` [PATCH v3 03/11] md/raid5: allocate and free pages of r5pages Yufen Yu
2020-05-27 13:19 ` [PATCH v3 04/11] md/raid5: set correct page offset for bi_io_vec in ops_run_io() Yufen Yu
2020-05-27 13:19 ` [PATCH v3 05/11] md/raid5: set correct page offset for async_copy_data() Yufen Yu
2020-05-27 13:19 ` [PATCH v3 06/11] md/raid5: add new xor function to support different page offset Yufen Yu
2020-05-27 13:19 ` [PATCH v3 07/11] md/raid5: add offset array in scribble buffer Yufen Yu
2020-05-27 13:19 ` [PATCH v3 08/11] md/raid5: compute xor with correct page offset Yufen Yu
2020-05-27 13:19 ` [PATCH v3 09/11] md/raid6: let syndrome computor support different " Yufen Yu
2020-05-27 13:19 ` [PATCH v3 10/11] md/raid6: compute syndrome with correct " Yufen Yu
2020-05-27 13:19 ` [PATCH v3 11/11] raid6test: adaptation with syndrome function Yufen Yu
2020-05-28 14:10 ` [PATCH v3 00/11] md/raid5: set STRIPE_SIZE as a configurable value Song Liu
2020-05-28 14:28   ` Song Liu
2020-05-29  9:32     ` Yufen Yu [this message]
2020-05-28 22:07 ` Guoqing Jiang
2020-05-29 11:49   ` Yufen Yu
2020-05-29 12:22     ` Guoqing Jiang
2020-05-30  2:15       ` Yufen Yu
2020-06-01 14:02         ` Guoqing Jiang
2020-06-02  6:59           ` Song Liu
2020-06-04 13:17             ` Yufen Yu

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