From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:51980) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UfQE6-0007K7-RU for qemu-devel@nongnu.org; Thu, 23 May 2013 03:46:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UfQDz-0005QJ-VT for qemu-devel@nongnu.org; Thu, 23 May 2013 03:46:18 -0400 Received: from mail-we0-x236.google.com ([2a00:1450:400c:c03::236]:54478) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UfQDz-0005Q6-Pl for qemu-devel@nongnu.org; Thu, 23 May 2013 03:46:11 -0400 Received: by mail-we0-f182.google.com with SMTP id q57so1627322wes.13 for ; Thu, 23 May 2013 00:46:11 -0700 (PDT) Date: Thu, 23 May 2013 09:46:07 +0200 From: Stefan Hajnoczi Message-ID: <20130523074607.GA2921@stefanha-thinkpad.redhat.com> References: <1369198655-25156-1-git-send-email-akong@redhat.com> <20130522093227.GB30148@stefanha-thinkpad.redhat.com> <20130522134821.GB2051@t430s.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130522134821.GB2051@t430s.nay.redhat.com> Subject: Re: [Qemu-devel] [PATCH] kvm: add detail error message when fail to add ioeventfd List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Amos Kong Cc: kvm@vger.kernel.org, gleb@redhat.com, qemu-devel@nongnu.org On Wed, May 22, 2013 at 09:48:21PM +0800, Amos Kong wrote: > On Wed, May 22, 2013 at 11:32:27AM +0200, Stefan Hajnoczi wrote: > > On Wed, May 22, 2013 at 12:57:35PM +0800, Amos Kong wrote: > > > I try to hotplug 28 * 8 multiple-function devices to guest with > > > old host kernel, ioeventfds in host kernel will be exhausted, then > > > qemu fails to allocate ioeventfds for blk/nic devices. > > > > > > It's better to add detail error here. > > > > > > Signed-off-by: Amos Kong > > > --- > > > kvm-all.c | 4 ++++ > > > 1 files changed, 4 insertions(+), 0 deletions(-) > > > > It would be nice to make kvm bus scalable so that the hardcoded > > in-kernel I/O device limit can be lifted. > > I had increased kernel NR_IOBUS_DEVS to 1000 (a limitation is needed for > security) in last Mar, and make resizing kvm_io_range array dynamical. The maximum should not be hardcoded. File descriptor, maximum memory, etc are all controlled by rlimits. And since ioeventfds are file descriptors they are already limited by the maximum number of file descriptors. Why is there a need to impose a hardcoded limit? Stefan