linux-kernel - Re: [PATCH] f2fs: introduce DEFAULT_IO_TIMEOUT

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Date:   Thu, 26 Dec 2019 17:38:42 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Vyacheslav Dubeyko <slava@...eyko.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>
CC:     Jaegeuk Kim <jaegeuk@...nel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Chao Yu <chao@...nel.org>,
        Linux FS Devel <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH] f2fs: introduce DEFAULT_IO_TIMEOUT_JIFFIES

On 2019/12/25 17:58, Vyacheslav Dubeyko wrote:
> On Mon, 2019-12-23 at 09:41 +0100, Geert Uytterhoeven wrote:
>> Hi,
>>
>> CC linux-fsdevel
>>
>> On Mon, Dec 23, 2019 at 5:01 AM Chao Yu <yuchao0@...wei.com> wrote:
>>> As Geert Uytterhoeven reported:
>>>
>>> for parameter HZ/50 in congestion_wait(BLK_RW_ASYNC, HZ/50);
>>>
>>> On some platforms, HZ can be less than 50, then unexpected 0
>>> timeout
>>> jiffies will be set in congestion_wait().
>>>
> 
> 
> It looks like that HZ could have various value on diferent platforms.
> So, why does it need to divide HZ on 50? Does it really necessary?

I guess this code was copied from other filesystems, I have no idea why
we should use HZ/50 as timeout interval value.

> Could it be used HZ only without the division operation?

Actually, as Geert pointed out, we can handle that zeroed value parameter
inside congestion_wait() to cover all filesystems use cases.

Thanks,

> 
> Thanks,
> Viacheslav Dubeyko.
> 
> 
> .
>