From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Vyacheslav Dubeyko <slava@dubeyko.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-f2fs-devel@lists.sourceforge.net,
Linux FS Devel <linux-fsdevel@vger.kernel.org>,
Jaegeuk Kim <jaegeuk@kernel.org>
Subject: Re: [f2fs-dev] [PATCH] f2fs: introduce DEFAULT_IO_TIMEOUT_JIFFIES
Date: Thu, 26 Dec 2019 11:43:38 +0100 [thread overview]
Message-ID: <CAMuHMdV5VtR+vgYKcZtvcz16GPp9YLG_ecAeDsiNCreP4rYKjw@mail.gmail.com> (raw)
In-Reply-To: <1cc2d2a093ebb15a1fc6eb96d683e918a8d5a7d4.camel@dubeyko.com>
Hi Vyacheslav,
On Wed, Dec 25, 2019 at 10:58 AM Vyacheslav Dubeyko <slava@dubeyko.com> wrote:
> On Mon, 2019-12-23 at 09:41 +0100, Geert Uytterhoeven wrote:
> > On Mon, Dec 23, 2019 at 5:01 AM Chao Yu <yuchao0@huawei.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?
> Could it be used HZ only without the division operation?
A timeout of HZ means 1 second.
HZ/50 means 20 ms, but has the risk of being zero, if HZ < 50.
If you want to use a timeout of 20 ms, you best use msecs_to_jiffies(20),
as that takes care of the special cases, and never returns 0.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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next prev parent reply other threads:[~2019-12-26 10:44 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-23 4:00 [f2fs-dev] [PATCH] f2fs: introduce DEFAULT_IO_TIMEOUT_JIFFIES Chao Yu
2019-12-23 8:41 ` Geert Uytterhoeven
2019-12-25 9:58 ` Vyacheslav Dubeyko
2019-12-26 9:38 ` Chao Yu
2019-12-26 10:43 ` Geert Uytterhoeven [this message]
2019-12-26 13:08 ` Vyacheslav Dubeyko
2019-12-26 13:16 ` Geert Uytterhoeven
2019-12-26 3:42 ` Chao Yu
2019-12-31 12:52 ` Matthew Wilcox
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