On Mon, Mar 23, 2015 at 1:36 PM, Ian Campbell <ian.campb...@citrix.com> wrote:
> On Sat, 2015-03-21 at 13:34 +0100, Christoffer Dall wrote: > > Hi, > > > > I have been experiencing a problematic crash running Xen on m400 over > > the last few days. I already spoke to Ian and Stefano about this, but > > thought I'd summarize what I've seen so far and loop in a wider > > audience. > > > > The basic setup is this: > > - Two m400 nodes, one running Linux bare-metal, the other running > > Xen. > > - The Xen node runs Dom0 and 1 DomU > > - The m400 has a Mellanox Connectx-3 PCIe 10G ethernet card with two > > parts on it > > - Dom0 uses NAT forwarding from Dom0's eth0 (which is connected to > > the internet) and regular bridging to eth1 which is connected to a > > private VLAN to the bare-metal node > > - Dom0 and DomU are configured with 14GB of ram, 4 cpus each > > - DomU runs apache2 serving the GCC manual (see > > > https://github.com/chazy/kvmperf/blob/master/cmdline_tests/apache_install.sh > ) > > > > The bare-metal node runs apache bench, like this: "ab -n 100000 -c 100 > > > http://secure-web.cisco.com/1r5tZ8-7RF8gHRANwFdizEZzgeMsjxVO0yKbYiV4zy7LeiUfYBXMkFq7FGW_SZ1x-VxdzyK-ErDsOUiQ9z2x-Ny7XkL_loHP8ene_BuNFscGyWmQ3r6CtXAYaZCY4xRmmPT1uJOsZDLMu7j-LfCOGmQDSdBwgW7QYukI2bCtTrXM/http%3A%2F%2F10.10.1.120%2Fgcc%2Findex.html > " > > > > (10.10.1.120 is the DomU IP address of the bridged interface to eth1) > > > > What happens now is that the entire Xen node goes down. I see various > > errors in the kernel log, some examples: > > http://pastebin.ubuntu.com/10642148/ > > http://pastebin.ubuntu.com/10642177/ > > http://pastebin.ubuntu.com/10642181/ > > http://pastebin.ubuntu.com/10635573/ > > > > > > All Linux kernels are 3.18 plus some tweaks for the m400 cartridge: > > https://github.com/columbia/linux-kvm-arm/tree/columbia-armvirt-3.18 > > Is it worth adding > > https://git.kernel.org/cgit/linux/kernel/git/arm64/linux.git/commit/?id=285994a62c80f1d72c6924282bcb59608098d5ec > to your kernel? It isn't Xen specific but it's perhaps possible that Xen > opens the window wider. > > How confident are you in > > https://github.com/columbia/linux-kvm-arm/commit/5e29cb0478f3d90e4f568d6bea6840960331bcbb > ? > (although I suppose you aren't running in ACPI mode if you are running > Xen?) > I'm not confident at all, but Linux (last I checked was v3.19) doesn't boot without it, so not sure if there's an alternative? Mark? > > If we think the issue might be to do with coherency of foreign mappings > undergoing i/o from dom0 and we've already ruled out disk (by using a > loopback mounted rootfs) then it might be worth bodging netback to > always copy too. > > Adding a call to skb_orphan_frags right before the netif_receive_skb in > drivers/net/xen-netback/netback.c:xenvif_tx_submit is a simple but > rather inefficient way of doing that (so I hope it doesn't perturb the > issue). > I'll be happy to try this. > > Stefano (who is more familiar with the Linux swiotlb side of things than > me) is travelling this week so he'll be on West coast time, not sure > when he gets off a plane nor if he's on email anyway (he's at ELC + this > ARM ACPI thing) > > ok, we'll see what happens. -Christoffer
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