From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.71) id 1QRRBF-0006QM-R6 for mharc-qemu-trivial@gnu.org; Tue, 31 May 2011 11:48:29 -0400 Received: from eggs.gnu.org ([140.186.70.92]:49958) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QRRBD-0006Q9-EA for qemu-trivial@nongnu.org; Tue, 31 May 2011 11:48:28 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QRRBA-0003DY-RB for qemu-trivial@nongnu.org; Tue, 31 May 2011 11:48:27 -0400 Received: from mail-gw0-f45.google.com ([74.125.83.45]:60209) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QRRBA-0003DR-OL; Tue, 31 May 2011 11:48:24 -0400 Received: by gwb19 with SMTP id 19so2185410gwb.4 for ; Tue, 31 May 2011 08:48:23 -0700 (PDT) Received: by 10.150.74.17 with SMTP id w17mr5117644yba.274.1306856903766; Tue, 31 May 2011 08:48:23 -0700 (PDT) Received: from [192.168.0.107] (cpe-70-123-132-139.austin.res.rr.com [70.123.132.139]) by mx.google.com with ESMTPS id q6sm71646yba.12.2011.05.31.08.48.22 (version=TLSv1/SSLv3 cipher=OTHER); Tue, 31 May 2011 08:48:22 -0700 (PDT) Message-ID: <4DE50DC5.2060806@codemonkey.ws> Date: Tue, 31 May 2011 10:48:21 -0500 From: Anthony Liguori User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110424 Lightning/1.0b2 Thunderbird/3.1.10 MIME-Version: 1.0 To: Alexander Graf References: <1306705831-59385-1-git-send-email-andreas.faerber@web.de> <4DE4F16D.6030009@codemonkey.ws> <4DE4F5E2.5020906@siemens.com> <4DE4FAA1.7080109@codemonkey.ws> <4DE5011C.80000@siemens.com> <98DD53CD-B6E2-4739-A952-0F21019485A4@suse.de> In-Reply-To: <98DD53CD-B6E2-4739-A952-0F21019485A4@suse.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 2) X-Received-From: 74.125.83.45 Cc: "qemu-trivial@nongnu.org" , Jan Kiszka , Marcelo Tosatti , "qemu-devel@nongnu.org" , =?ISO-8859-1?Q?Andreas_F=E4rber?= , Avi Kivity Subject: Re: [Qemu-trivial] [Qemu-devel] [PATCH] Use SIGIO with caution X-BeenThere: qemu-trivial@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 31 May 2011 15:48:28 -0000 On 05/31/2011 10:44 AM, Alexander Graf wrote: > > On 31.05.2011, at 16:54, Jan Kiszka wrote: > >> On 2011-05-31 16:26, Anthony Liguori wrote: >>> On 05/31/2011 09:06 AM, Jan Kiszka wrote: >>>> On 2011-05-31 15:47, Anthony Liguori wrote: >>>>> On 05/29/2011 04:50 PM, Andreas Färber wrote: >>>>>> BeOS and Haiku don't define SIGIO. When undefined, it won't arrive >>>>>> and doesn't need to be blocked. >>>>>> >>>>>> Signed-off-by: Andreas Färber >>>>> >>>>> Anything to do with signal masks is never a trivial patch BTW... >>>>> >>>>> But I actually think explicit handling of SIGIO is unneeded. I think >>>>> this is a hold over from the pre-I/O thread days where we selectively >>>>> set SIGIO on certain file descriptors to make sure that when an IO fd >>>>> became readable, we received a signal to break out of the KVM emulation >>>>> loop. >>>>> >>>>> Can the folks on CC confirm/deny? >>>>> >>>>> I can't see any use of SIGIO in the current source tree. >>>> >>>> At least qemu-timer.c uses SIGIO in HPET mode. That only applies to >>>> Linux hosts, though. >>> >>> Is there any reason we still carry multiple timer implementations these >>> days? >>> >>> HPET shouldn't be any better than dynticks. >> >> On any recent kernel, for sure. BTW, the same applies to the RTC timer. > > So the obvious change would be to introduce CONFIG_HPET, ifdef the SIGIO handling on that and also ifdef the host hpet handling code on it? That way it's documented well and can preferably even be turned off with --disable-host-hpet during configure time, which we can then slowly turn to the default. Or just remove hpet and rtc. Does anyone really object to that? Regards, Anthony Liguori > > Alex > > From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:49973) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QRRBF-0006QH-D5 for qemu-devel@nongnu.org; Tue, 31 May 2011 11:48:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QRRBE-0003E8-Il for qemu-devel@nongnu.org; Tue, 31 May 2011 11:48:29 -0400 Message-ID: <4DE50DC5.2060806@codemonkey.ws> Date: Tue, 31 May 2011 10:48:21 -0500 From: Anthony Liguori MIME-Version: 1.0 References: <1306705831-59385-1-git-send-email-andreas.faerber@web.de> <4DE4F16D.6030009@codemonkey.ws> <4DE4F5E2.5020906@siemens.com> <4DE4FAA1.7080109@codemonkey.ws> <4DE5011C.80000@siemens.com> <98DD53CD-B6E2-4739-A952-0F21019485A4@suse.de> In-Reply-To: <98DD53CD-B6E2-4739-A952-0F21019485A4@suse.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [PATCH] Use SIGIO with caution List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf Cc: "qemu-trivial@nongnu.org" , Jan Kiszka , Marcelo Tosatti , "qemu-devel@nongnu.org" , =?ISO-8859-1?Q?Andreas_F=E4rber?= , Avi Kivity On 05/31/2011 10:44 AM, Alexander Graf wrote: > > On 31.05.2011, at 16:54, Jan Kiszka wrote: > >> On 2011-05-31 16:26, Anthony Liguori wrote: >>> On 05/31/2011 09:06 AM, Jan Kiszka wrote: >>>> On 2011-05-31 15:47, Anthony Liguori wrote: >>>>> On 05/29/2011 04:50 PM, Andreas Färber wrote: >>>>>> BeOS and Haiku don't define SIGIO. When undefined, it won't arrive >>>>>> and doesn't need to be blocked. >>>>>> >>>>>> Signed-off-by: Andreas Färber >>>>> >>>>> Anything to do with signal masks is never a trivial patch BTW... >>>>> >>>>> But I actually think explicit handling of SIGIO is unneeded. I think >>>>> this is a hold over from the pre-I/O thread days where we selectively >>>>> set SIGIO on certain file descriptors to make sure that when an IO fd >>>>> became readable, we received a signal to break out of the KVM emulation >>>>> loop. >>>>> >>>>> Can the folks on CC confirm/deny? >>>>> >>>>> I can't see any use of SIGIO in the current source tree. >>>> >>>> At least qemu-timer.c uses SIGIO in HPET mode. That only applies to >>>> Linux hosts, though. >>> >>> Is there any reason we still carry multiple timer implementations these >>> days? >>> >>> HPET shouldn't be any better than dynticks. >> >> On any recent kernel, for sure. BTW, the same applies to the RTC timer. > > So the obvious change would be to introduce CONFIG_HPET, ifdef the SIGIO handling on that and also ifdef the host hpet handling code on it? That way it's documented well and can preferably even be turned off with --disable-host-hpet during configure time, which we can then slowly turn to the default. Or just remove hpet and rtc. Does anyone really object to that? Regards, Anthony Liguori > > Alex > >