From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:39591) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RveK6-0005dI-C6 for qemu-devel@nongnu.org; Thu, 09 Feb 2012 19:26:47 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RveK5-00018t-CP for qemu-devel@nongnu.org; Thu, 09 Feb 2012 19:26:46 -0500 Received: from relay1.mentorg.com ([192.94.38.131]:64005) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RveK5-00018m-5Z for qemu-devel@nongnu.org; Thu, 09 Feb 2012 19:26:45 -0500 From: Paul Brook Date: Fri, 10 Feb 2012 00:26:40 +0000 References: <1327688498-12362-6-git-send-email-stefano.stabellini@eu.citrix.com> In-Reply-To: <1327688498-12362-6-git-send-email-stefano.stabellini@eu.citrix.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-6" Content-Transfer-Encoding: 7bit Message-Id: <201202100026.40727.paul@codesourcery.com> Subject: Re: [Qemu-devel] [PATCH v3 6/6] qemu_calculate_timeout: increase minimum timeout to 1h List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: pbonzini@redhat.com, xen-devel@lists.xensource.com, avi@redhat.com, Stefano Stabellini > There is no reason why the minimum timeout should be 1sec, it could > easily be 1h and we would save lots of cpu cycles. No. The reason we have this is because there are bits of code that rely on polling. IIRC slirp and the floppy DMA engine were the main culprits. qemu_calculate_timeout is an ugly hack to poll at least once a second, allowing the guest to make forward progress when we miss an event. If you think you've fixed all those polling places then you should remove the timeout altogether and block indefinitely. A 1h timeout is almost certainly not the right answer. Paul