Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753366Ab0HTPdK (ORCPT ); Fri, 20 Aug 2010 11:33:10 -0400 Received: from cantor2.suse.de ([195.135.220.15]:51029 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753342Ab0HTPdH (ORCPT ); Fri, 20 Aug 2010 11:33:07 -0400 Date: Fri, 20 Aug 2010 08:33:46 -0700 From: Greg KH To: "Kirill A. Shutemov" Cc: Andrew Morton , "H. Peter Anvin" , Alexander Shishkin , Thomas Gleixner , John Stultz , Martin Schwidefsky , Jon Hunter , Ingo Molnar , Peter Zijlstra , "Paul E. McKenney" , David Howells , Avi Kivity , John Kacur , Chris Friesen , Kay Sievers , linux-kernel@vger.kernel.org Subject: Re: [PATCH] [RFCv2] notify userspace about time changes Message-ID: <20100820153346.GA10830@suse.de> References: <1282139739-23832-1-git-send-email-virtuoso@slind.org> <20100818155702.bc62b2a6.akpm@linux-foundation.org> <4C6C7034.4050501@zytor.com> <20100818165303.dd52695a.akpm@linux-foundation.org> <20100819040937.GA8646@suse.de> <20100819083612.GA13293@shutemov.name> <20100819153127.GC2985@suse.de> <20100820083723.GA18616@shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100820083723.GA18616@shutemov.name> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2415 Lines: 59 On Fri, Aug 20, 2010 at 11:37:23AM +0300, Kirill A. Shutemov wrote: > On Thu, Aug 19, 2010 at 08:31:27AM -0700, Greg KH wrote: > > On Thu, Aug 19, 2010 at 11:36:12AM +0300, Kirill A. Shutemov wrote: > > > On Wed, Aug 18, 2010 at 09:09:37PM -0700, Greg KH wrote: > > > > On Wed, Aug 18, 2010 at 04:53:03PM -0700, Andrew Morton wrote: > > > > > Is sysfs the right interface for this thing? Bear in mind that > > > > > CONFIG_SYSFS does exist. > > > > > > > > > > > + fd = open("/sys/kernel/time_notify", O_WRONLY); > > > > > > + fdprintf(fd, "%d 1 0 1 1", efd); > > > > > > > > > > why not > > > > > > > > > > sys_time_notify(efd, 1, 0, 1, 1); > > > > > > > > Yeah, that would be much better than a sysfs file, this is abusing the > > > > sysfs interface quite a lot. > > > > > > Do you really think, that increasing number of syscalls is better then > > > fs-based interfaces? > > > > As you are pretty much creating a new syscall here anyway, there is no > > problem with making it a real one, right? > > I think Linux has too many syscalls. Significant part these interfaces > would be better to map to a filesystem[s]. What is the difference between a syscall and a filesystem interface? They are both things that we can not change in the future and need to be preserved and documented. Don't be afraid of syscall's, they don't bite :) > > That way you can properly > > handle the user/kernel documentation and persistance over time (i.e. you > > can't change it.) > > On the other, hand properly designed fs-based interface requires less > modification of userspeace to use it. Acctually, you can use most of > fs-based intefaces directly from shell. No need in libc modifications and > utilities to use it from shell or other script language. > See cgroup, for example. > > > So yes, a syscall would be better, especially as this does not exactly > > fit into the model of sysfs, right? > > Yes, sysfs is not the best place for it, but... You just answered your own question. Please don't make it in sysfs, make it a syscall as it does not fit into sysfs. thanks, greg "constantly fighting to keep /sys/ from being like /proc/" k-h -- 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/