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Subject: Re: [PATCH -next v2 0/7] limit the number of plugged bio
To:     Song Liu <song@kernel.org>, Yu Kuai <yukuai1@huaweicloud.com>
Cc:     akpm@osdl.org, neilb@suse.de, linux-raid@vger.kernel.org,
        linux-kernel@vger.kernel.org, yi.zhang@huawei.com,
        yangerkun@huawei.com, "yukuai (C)" <yukuai3@huawei.com>
References: <20230426082031.1299149-1-yukuai1@huaweicloud.com>
 <a7246f63-b499-8b26-e27a-3d16abc18ced@huaweicloud.com>
 <CAPhsuW4ZVs0QbWhHibL4A4LG72Q9bPabjCY7ZZkcshTYf+vhbg@mail.gmail.com>
From:   Yu Kuai <yukuai1@huaweicloud.com>
Message-ID: <88d2b016-376c-d65d-ef04-d9cdf5d7b096@huaweicloud.com>
Date:   Sat, 13 May 2023 10:03:50 +0800
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Hi,

在 2023/05/13 8:50, Song Liu 写道:
> On Fri, May 12, 2023 at 2:43 AM Yu Kuai <yukuai1@huaweicloud.com> wrote:
>>
>> Hi,
>>
>> 在 2023/04/26 16:20, Yu Kuai 写道:
>>> From: Yu Kuai <yukuai3@huawei.com>
>>>
>>> Changes in v2:
>>>    - remove the patch to rename raid1-10.c
>>>
>>> This patchset tries to limit the number of plugged bio for raid1 and
>>> raid10, which is done in the last patch, other patches are some refactor
>>> and optimizations.
>>>
>>> This patchset is tested with a new test [1], this test triggers dirty
>>> pages writeback for 10s, and in the meantime checks disk inflight.
>>>
>>> Before this patchset, test will fail because inflight exceed threshold
>>> (threshold is set to 4096 in the test, in theory this can be mutch
>>>    greater as long as there are enough dirty pages and memory).
>>>
>>> After this patchset, inflight is within 96 (MAX_PLUG_BIO * copies).
>>>
>>> [1] https://lore.kernel.org/linux-raid/20230426073447.1294916-1-yukuai1@huaweicloud.com/
>>
>> Friendly ping...
> 
> I am sorry for the delay.
> 
> The set looks good overall, but I will need some more time to take a closer
> look. A few comments/questions:
> 
> 1. For functions in raid1-10.c, let's prefix them with raid1_ instead of md_*.
Ok, I'll change that in v3.

> 2. Do we need unplug_wq to be per-bitmap? Would a shared queue work?

I think this can work, the limitation is that global workqueue can
support 256 queued work at a time, but this should be enough.

Thanks,
Kuai
> 
> Thanks,
> Song
> .
>