From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:50807) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SFmLV-0003CB-1F for qemu-devel@nongnu.org; Thu, 05 Apr 2012 09:03:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SFmLO-0006Kv-PG for qemu-devel@nongnu.org; Thu, 05 Apr 2012 09:03:24 -0400 Received: from thoth.sbs.de ([192.35.17.2]:22743) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SFmLO-0006KI-FT for qemu-devel@nongnu.org; Thu, 05 Apr 2012 09:03:18 -0400 Message-ID: <4F7D980B.2040002@siemens.com> Date: Thu, 05 Apr 2012 15:03:07 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <6e10c02cbb87fe30703de848455593df41ec7f4b.1333623555.git.jan.kiszka@siemens.com> <4F7D887B.1030104@siemens.com> <4F7D921E.9040003@redhat.com> <4F7D9691.9090507@redhat.com> <4F7D9735.7040509@siemens.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: malc Cc: Kevin Wolf , Paolo Bonzini , Anthony Liguori , "qemu-devel@nongnu.org" , Peter Maydell On 2012-04-05 15:00, malc wrote: > On Thu, 5 Apr 2012, Jan Kiszka wrote: > >> On 2012-04-05 14:56, Paolo Bonzini wrote: >>> Il 05/04/2012 14:53, malc ha scritto: >>>> On Thu, 5 Apr 2012, Paolo Bonzini wrote: >>>> >>>>> Il 05/04/2012 14:30, malc ha scritto: >>>>>>>> Would save that "* 1000". I just wondered why we do not use it elsewhere >>>>>>>> in QEMU and was reluctant to risk some BSD breakage. >>>>>>>> >>>>>> It's probably worth mentioning that using anything other than >>>>>> clock_gettime and CLOCK_MONOTONING (as well as setting proper pthread >>>>>> clock attr on the condition variable) is prone to the surprises (such >>>>>> as NTP corrections and daylight saving changes). >>>>> >>>>> I was about to suggest the same, but how widespread is support for >>>>> pthread_condattr_setclock? >>>> >>>> If it's not all is lost anyway. >>> >>> Only once every year. :) >> >> ...and not for the current user of this service which do not care that >> much about the timeout and a potential delay or early shot. >> > > An hour of potential delay mind you. Nope, look at posix-aio-compat. It's an optimization to keep the number worker threads under control. Granted, time adjustments can make qemu_cond_timedwait in this primitive (but easily portable) form less useful for other purposes. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux