From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753882AbaEUWfR (ORCPT ); Wed, 21 May 2014 18:35:17 -0400 Received: from mail-la0-f43.google.com ([209.85.215.43]:55295 "EHLO mail-la0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753407AbaEUWfP (ORCPT ); Wed, 21 May 2014 18:35:15 -0400 Date: Thu, 22 May 2014 02:35:11 +0400 From: Cyrill Gorcunov To: Thomas Gleixner Cc: linux-kernel@vger.kernel.org, shawn@churchofgit.com, akpm@linux-foundation.org, avagin@openvz.org, xemul@parallels.com, vdavydov@parallels.com Subject: Re: [patch 3/3] timerfd: Implement write method Message-ID: <20140521223511.GI12819@moon> References: <20140428212517.200264067@openvz.org> <20140428213301.507657833@openvz.org> <20140521215707.GH12819@moon> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 22, 2014 at 07:12:30AM +0900, Thomas Gleixner wrote: > > There is a world outside of checkpoint/restore, really. Yes, I simply don't know who else might use this write() functionality for other purpose, I mean i don't see a point to use it for anything else. > So what's the semantics of that write function? We really want to have > that agreed on and documented in the man page. The idea was to provide a way to setup @ticks into (nonzero) value which we get from show_fdinfo output. Then when we restore it we setup the timer and set @ticks to the value it had at dump moment. > Right now the write will just update the ticks and nothing else. So > what if there is a waiter already? What if there is a timer armed? > > Can you please describe how checkpoint/restore is going to use all of > this. How is the timer restored and how/when is the reader which was > waiting in read/poll at the time of suspend reattached to it. Thomas, I see what you mean. Need to think (I must admit I forgot about polling of timerfds :( I were to restore timerfds like this - fetch data from fdinfo - use timer_create/settime to arm it - write @ticks then but i didn't try restore polling waiters, my bad. Letme rework this trying addressing your comments.