This patch sets the coherent DMA mask to 64-bit after the be2net driver
has been acknowledged that the system is 64-bit DMA capable. The coherent
DMA mask is examined by the Intel IOMMU driver to determine whether to
allow pass through context mapping for all devices. With this patch, the
be2net driver combined with be2net compatible hardware provides
comparable performance to the case where vt-d is disabled. The main use
case for this change is to decrease the time necessary to copy virtual
machine memory during KVM live migration instantiations.
This patch was tested on a system that enables the IOMMU in non-coherent
mode. Two DMA remapper issues were encountered in the previous version and
both patches have been committed.
commit ea2447f700cab264019b52e2b417d689e052dcfd
commit 2e12bc29fc5a12242d68e11875db3dd58efad9ff
The performance of this patch was measured with netperf with vt-d
enabled and disabled along with kernel boot parameters intel_iommu
and iommu. The command and parameters used in the netperf runs along
with results are as follows:
# netperf -c -p 12865 -H 10.10.0.2 -t TCP_STREAM -l 60
vt-d enabled and intel-iommu=on
Recv Send Send Utilization Service Demand
Socket Socket Message Elapsed Send Recv Send Recv
Size Size Size Time Throughput local remote local remote
bytes bytes bytes secs. 10^6bits/s % S % U us/KB us/KB
87380 16384 16384 60.00 4636.58 16.76 -1.00 1.777 -1.000
87380 16384 16384 60.00 4718.79 17.30 -1.00 1.802 -1.000
87380 16384 16384 60.00 4566.91 18.04 -1.00 1.942 -1.000
vt-d enabled
Recv Send Send Utilization Service Demand
Socket Socket Message Elapsed Send Recv Send Recv
Size Size Size Time Throughput local remote local remote
bytes bytes bytes secs. 10^6bits/s % S % U us/KB us/KB
87380 16384 16384 60.00 6837.12 7.21 -1.00 0.518 -1.000
87380 16384 16384 60.00 6956.20 6.38 -1.00 0.450 -1.000
87380 16384 16384 60.00 6903.63 6.75 -1.00 0.481 -1.000
vt-d disabled
Recv Send Send Utilization Service Demand
Socket Socket Message Elapsed Send Recv Send Recv
Size Size Size Time Throughput local remote local remote
bytes bytes bytes secs. 10^6bits/s % S % U us/KB us/KB
87380 16384 16384 60.00 6909.70 6.57 -1.00 0.467 -1.000
87380 16384 16384 60.00 6811.79 6.90 -1.00 0.498 -1.000
87380 16384 16384 60.00 6861.32 6.71 -1.00 0.481 -1.000
vt-d enabled and intel_iommu=on and iommu=pt
Recv Send Send Utilization Service Demand
Socket Socket Message Elapsed Send Recv Send Recv
Size Size Size Time Throughput local remote local remote
bytes bytes bytes secs. 10^6bits/s % S % U us/KB us/KB
87380 16384 16384 60.00 6768.45 7.30 -1.00 0.530 -1.000
87380 16384 16384 60.00 6841.40 7.39 -1.00 0.531 -1.000
87380 16384 16384 60.00 6861.78 5.68 -1.00 0.407 -1.000
Craig Hada (1):
drivers/net: Enable IOMMU pass through for be2net
drivers/net/ethernet/emulex/benet/be_main.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)
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