From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 9B72140B for ; Mon, 27 Jul 2015 13:03:31 +0000 (UTC) Received: from v094114.home.net.pl (v094114.home.net.pl [79.96.170.134]) by smtp1.linuxfoundation.org (Postfix) with SMTP id 4251779 for ; Mon, 27 Jul 2015 13:03:29 +0000 (UTC) From: "Rafael J. Wysocki" To: Josh Triplett Date: Mon, 27 Jul 2015 15:30:24 +0200 Message-ID: <1591143.F5lcGfdGXX@vostro.rjw.lan> In-Reply-To: <20150726001600.GA19810@x> References: <1489458.8WDRattPkl@vostro.rjw.lan> <3566742.dUiIOvU9qh@vostro.rjw.lan> <20150726001600.GA19810@x> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Cc: "Brown, Len" , "ksummit-discuss@lists.linuxfoundation.org" , Alan Stern , Kristen Carlson Accardi , Grant Likely Subject: Re: [Ksummit-discuss] [TECH TOPIC] System-wide interface to specify the level of PM tuning List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Saturday, July 25, 2015 05:16:00 PM Josh Triplett wrote: > On Sun, Jul 26, 2015 at 02:03:55AM +0200, Rafael J. Wysocki wrote: > > On Saturday, July 25, 2015 12:50:16 PM Josh Triplett wrote: [cut] > > > > Say the user has a new machine and doesn't know which tunables can be safely > > enabled on it. The only way to check is to toggle all of them and see if > > anything breaks. The difficulty here is that the user actually needs to > > know about all of them which takes quite a bit of research and if nothing > > breaks really that's a fair amount of work pretty much in vain. A global > > switch would make it somewhat easier for the lucky users whose systems > > don't break after toggling it. > > Odds are at least one thing will break, though, and if the user doesn't > know about all of the tunables they just changed, they won't necessarily > know how to diagnose the reason, especially if the failure is more > subtle and doesn't completely break the system. > > Perhaps, as a start towards this, we could document all the "might or > might not work" power management tunables in one place, and document > what might go wrong if they don't work on your system. That could then > easily become an /etc/sysctl.d file to toggle them all. And even if we > offer a single global "dangerous PM tunables" switch, that document > would help identify what might go wrong and help re-disable the things > that don't work. That sounds like a good idea to me. Thanks, Rafael