From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: Re: [PATCH 3/3] kvm tools: Make virtio-blk kvm__irq_line thread safe Date: Fri, 29 Apr 2011 11:29:40 +0300 Message-ID: <1304065780.10069.19.camel@lappy> References: <1304058985-13833-1-git-send-email-asias.hejun@gmail.com> <1304058985-13833-3-git-send-email-asias.hejun@gmail.com> <20110429064433.GB13893@elte.hu> <4DBA681C.4090707@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Asias He , Ingo Molnar , Cyrill Gorcunov , Prasad Joshi , kvm@vger.kernel.org To: Pekka Enberg Return-path: Received: from mail-ww0-f44.google.com ([74.125.82.44]:51197 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757613Ab1D2I3w (ORCPT ); Fri, 29 Apr 2011 04:29:52 -0400 Received: by wwa36 with SMTP id 36so4034302wwa.1 for ; Fri, 29 Apr 2011 01:29:51 -0700 (PDT) In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Fri, 2011-04-29 at 10:55 +0300, Pekka Enberg wrote: > On Fri, Apr 29, 2011 at 10:26 AM, Asias He wrote: > >> Yes, looks strange. Asias, did you see some bad behavior that this > >> fixes? > > > > Yes. I see random virtio net hangs with scp test. This commit > > 847838c573f4c04be7547f508a99be2dfdefb4fd triggers this problem as we are > > using separte irq lines for each virtio devices instead of sharing one > > irq line for all virtio devices. > > That's interesting. So reverting that commit makes the hangs go away? I was able to reproduce the hang by running 'ping -f' from the guest to the host and from the host to the guest. >>From debugging I found that virtio-net's VIRTIO_PCI_QUEUE_NOTIFY doesn't get called once it's hung. The hang does seems to go away once I revert 847838c573f4c04be7547f508a99be2dfdefb4fd . -- Sasha.