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Thu, 26 Dec 2019 02:43:49 -0800 (PST) MIME-Version: 1.0 References: <20191223040020.109570-1-yuchao0@huawei.com> <1cc2d2a093ebb15a1fc6eb96d683e918a8d5a7d4.camel@dubeyko.com> In-Reply-To: <1cc2d2a093ebb15a1fc6eb96d683e918a8d5a7d4.camel@dubeyko.com> From: Geert Uytterhoeven Date: Thu, 26 Dec 2019 11:43:38 +0100 Message-ID: To: Vyacheslav Dubeyko X-Headers-End: 1ikQcV-00FbrY-Fh Subject: Re: [f2fs-dev] [PATCH] f2fs: introduce DEFAULT_IO_TIMEOUT_JIFFIES X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Linux Kernel Mailing List , linux-f2fs-devel@lists.sourceforge.net, Linux FS Devel , Jaegeuk Kim Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net Hi Vyacheslav, On Wed, Dec 25, 2019 at 10:58 AM Vyacheslav Dubeyko wrote: > On Mon, 2019-12-23 at 09:41 +0100, Geert Uytterhoeven wrote: > > On Mon, Dec 23, 2019 at 5:01 AM Chao Yu 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 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel