From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:51427) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SSD8W-0001RH-0H for qemu-devel@nongnu.org; Wed, 09 May 2012 16:05:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SSD8U-0001Ky-0v for qemu-devel@nongnu.org; Wed, 09 May 2012 16:05:23 -0400 Received: from e3.ny.us.ibm.com ([32.97.182.143]:50623) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SSD8T-0001Kt-Su for qemu-devel@nongnu.org; Wed, 09 May 2012 16:05:21 -0400 Received: from /spool/local by e3.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 9 May 2012 16:05:18 -0400 Received: from d01relay06.pok.ibm.com (d01relay06.pok.ibm.com [9.56.227.116]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id DA3F46E813F for ; Wed, 9 May 2012 16:02:10 -0400 (EDT) Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay06.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q49K1qI623789608 for ; Wed, 9 May 2012 16:01:52 -0400 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q49K1qE7032416 for ; Wed, 9 May 2012 16:01:52 -0400 Message-ID: <4FAACD2F.30702@us.ibm.com> Date: Wed, 09 May 2012 15:01:51 -0500 From: Anthony Liguori MIME-Version: 1.0 References: <4FAAC3A3.5040503@siemens.com> <4FAAC521.5000907@msgid.tls.msk.ru> <4FAAC6B2.7040009@siemens.com> <4FAACA0A.5040602@us.ibm.com> <4FAACC0F.9080702@siemens.com> In-Reply-To: <4FAACC0F.9080702@siemens.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 1.1] coroutine: Avoid ucontext usage on i386 Linux host List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: Kevin Wolf , Peter Maydell , Michael Tokarev , qemu-devel On 05/09/2012 02:57 PM, Jan Kiszka wrote: > On 2012-05-09 16:48, Anthony Liguori wrote: >> On 05/09/2012 02:34 PM, Jan Kiszka wrote: >>>> Can't we resort to the SIGUSR1 workaround for the time being, while >>>> no RT signals are in actual use, and just have the time to let the >>>> kernel side to fix the things up before some actual RTsig user will >>>> emerge in qemu? I think it is a bit more conservative approach, >>>> especially having in mind the minority of users this issue affects >>>> (only 32/64 mixed environment). I'd favor for this variant, and >>>> it looks like I'm the "main" 32/64bit user of qemu in this world :) >>> >>> Most conservative is definitely this patch, not switching to SIGUSR1, >>> hoping that no other RT signal user shows up until current kernel are no >>> longer in use. >> >> Sorry, how is using a totally different code path more conservative than using a >> different signal number? > > If the gthread version is not safe to use, why do we fall back to it? It's safe, but it's significantly slower. Regards, Anthony Liguori