Paolo Bonzini
2014-Aug-28 18:55 UTC
[virtio-dev] Re: [PATCH v2 0/4] virtio: Clean up scatterlists and use the DMA API
Il 28/08/2014 20:29, Christian Borntraeger ha scritto:>>> >> block seems to work, with net a simple ping works, iperf causes this: >> > >> > I neither see the bug, nor can I reproduce it on x86_64 on KVM. I >> > doubt that dma vs. non-dma is relevant. I tried -net user a -net tap >> > with iperf running in both directions. I also tried switching >> > virtio_pci into non-DMA-API mode. No errors. >> > >> > Is there any chance that you could instrument that BUG_ON to print n, >> > i, in_sgs, out_sgs, total_sg, total_in, and total_out? I assume this >> > is some oddity with patch 1, but I'm mystified. > Yes, its triggered by patch 1.What version of QEMU? Can you two cat the "features" file in the virtio-net device's sysfs directory? Paolo
Andy Lutomirski
2014-Aug-28 19:03 UTC
[virtio-dev] Re: [PATCH v2 0/4] virtio: Clean up scatterlists and use the DMA API
[removed virtio-dev -- I'm sick of bounces] On Thu, Aug 28, 2014 at 11:55 AM, Paolo Bonzini <pbonzini at redhat.com> wrote:> Il 28/08/2014 20:29, Christian Borntraeger ha scritto: >>>> >> block seems to work, with net a simple ping works, iperf causes this: >>> > >>> > I neither see the bug, nor can I reproduce it on x86_64 on KVM. I >>> > doubt that dma vs. non-dma is relevant. I tried -net user a -net tap >>> > with iperf running in both directions. I also tried switching >>> > virtio_pci into non-DMA-API mode. No errors. >>> > >>> > Is there any chance that you could instrument that BUG_ON to print n, >>> > i, in_sgs, out_sgs, total_sg, total_in, and total_out? I assume this >>> > is some oddity with patch 1, but I'm mystified. >> Yes, its triggered by patch 1. > > What version of QEMU? Can you two cat the "features" file in the > virtio-net device's sysfs directory?With vhost=on: # cat /sys/class/net/eth0/device/features 0000011000000001111101010001110000000000000000000000000000000000 Without vhost=on: # cat /sys/class/net/eth0/device/features 0000011000000001111101010001110000000000000000000000000000000000 Instrumenting the code says that indirect=1. --Andy
Christian Borntraeger
2014-Aug-28 19:18 UTC
[virtio-dev] Re: [PATCH v2 0/4] virtio: Clean up scatterlists and use the DMA API
On 28/08/14 21:03, Andy Lutomirski wrote:> [removed virtio-dev -- I'm sick of bounces] > > On Thu, Aug 28, 2014 at 11:55 AM, Paolo Bonzini <pbonzini at redhat.com> wrote: >> Il 28/08/2014 20:29, Christian Borntraeger ha scritto: >>>>>>> block seems to work, with net a simple ping works, iperf causes this: >>>>> >>>>> I neither see the bug, nor can I reproduce it on x86_64 on KVM. I >>>>> doubt that dma vs. non-dma is relevant. I tried -net user a -net tap >>>>> with iperf running in both directions. I also tried switching >>>>> virtio_pci into non-DMA-API mode. No errors. >>>>> >>>>> Is there any chance that you could instrument that BUG_ON to print n, >>>>> i, in_sgs, out_sgs, total_sg, total_in, and total_out? I assume this >>>>> is some oddity with patch 1, but I'm mystified. >>> Yes, its triggered by patch 1. >> >> What version of QEMU? Can you two cat the "features" file in the >> virtio-net device's sysfs directory? > > With vhost=on: > > # cat /sys/class/net/eth0/device/features > 0000011000000001111101010001110000000000000000000000000000000000>> Without vhost=on: > > # cat /sys/class/net/eth0/device/features > 0000011000000001111101010001110000000000000000000000000000000000 > > Instrumenting the code says that indirect=1. > > --Andy >I have 1100011111111111111101010001110000000000000000000000000000000000
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