Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751741AbbGEJGq (ORCPT ); Sun, 5 Jul 2015 05:06:46 -0400 Received: from netrider.rowland.org ([192.131.102.5]:56944 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752031AbbGEJGi (ORCPT ); Sun, 5 Jul 2015 05:06:38 -0400 Date: Sat, 4 Jul 2015 10:19:55 -0400 (EDT) From: Alan Stern X-X-Sender: stern@netrider.rowland.org To: "Rafael J. Wysocki" cc: Dave Chinner , Len Brown , Henrique de Moraes Holschuh , One Thousand Gnomes , Linux PM list , "linux-kernel@vger.kernel.org" , Len Brown Subject: Re: [PATCH 1/1] suspend: delete sys_sync() In-Reply-To: <1496051.AgsebokWnB@vostro.rjw.lan> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1716 Lines: 41 On Sat, 4 Jul 2015, Rafael J. Wysocki wrote: > The only argument against dropping sys_sync() from the suspend code path > I've seen in this thread that I entirely agree with is that it may lead to > regressions, because we've done it practically forever and it may hide latent > bugs somewhere in block drivers etc. Dropping it, though, is the only way > to see those bugs, if any, and if we want to ever fix them, we need to see > them. That's why I think that it may be a good idea to allow people to > drop it if they are willing to accept some extra risk (via the kernel > command line, for example). I'd be perfectly happy to have the sync selectable at runtime, one way or another. The three most reasonable options seem to be: kernel command line sysfs file sysctl setting The command line is less flexible (it can't be changed after booting). Either of the other two would be fine with me. > Moreover, question is if we really need to carry out the sync on *every* > suspend even if it is not pointless overall. That shouldn't really be > necessary if we suspend and resume often enough or if we resume only for > a while and then suspend again. Maybe it should be rate limited somehow > at least? For example, skip the sync if the system has been awake for < 100 ms? The cutoff time could also be controlled by the sysfs file: -1 => never sync, 0 => always sync, > 0 => sync if the system has been awake longer than the value. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/