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  1. 18 1月, 2014 32 次提交
  3. 17 1月, 2014 8 次提交
    • D
      Merge branch 'virtio_rx_merging' · cf84eb0b
      由 David S. Miller 提交于 
      Michael Dalton says:

====================
virtio-net: mergeable rx buffer size auto-tuning

The virtio-net device currently uses aligned MTU-sized mergeable receive
packet buffers. Network throughput for workloads with large average
packet size can be improved by posting larger receive packet buffers.
However, due to SKB truesize effects, posting large (e.g, PAGE_SIZE)
buffers reduces the throughput of workloads that do not benefit from GRO
and have no large inbound packets.

This patchset introduces virtio-net mergeable buffer size auto-tuning,
with buffer sizes ranging from aligned MTU-size to PAGE_SIZE. Packet
buffer size is chosen based on a per-receive queue EWMA of incoming
packet size.

To unify mergeable receive buffer memory allocation and improve
SKB frag coalescing, all mergeable buffer memory allocation is
migrated to per-receive queue page frag allocators.

The per-receive queue mergeable packet buffer size is exported via
sysfs, and the network device sysfs layer has been extended to add
support for device-specific per-receive queue sysfs attribute groups.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      cf84eb0b
    • M
      virtio-net: initial rx sysfs support, export mergeable rx buffer size · fbf28d78
      由 Michael Dalton 提交于 
      Add initial support for per-rx queue sysfs attributes to virtio-net. If
mergeable packet buffers are enabled, adds a read-only mergeable packet
buffer size sysfs attribute for each RX queue.
Suggested-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael Dalton <mwdalton@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      fbf28d78
    • M
      lib: Ensure EWMA does not store wrong intermediate values · 03144b58
      由 Michael Dalton 提交于 
      To ensure ewma_read() without a lock returns a valid but possibly
out of date average, modify ewma_add() by using ACCESS_ONCE to prevent
intermediate wrong values from being written to avg->internal.
Suggested-by: NEric Dumazet <eric.dumazet@gmail.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NMichael Dalton <mwdalton@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      03144b58
    • M
      net-sysfs: add support for device-specific rx queue sysfs attributes · a953be53
      由 Michael Dalton 提交于 
      Extend existing support for netdevice receive queue sysfs attributes to
permit a device-specific attribute group. Initial use case for this
support will be to allow the virtio-net device to export per-receive
queue mergeable receive buffer size.
Signed-off-by: NMichael Dalton <mwdalton@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      a953be53
    • M
      virtio-net: auto-tune mergeable rx buffer size for improved performance · ab7db917
      由 Michael Dalton 提交于 
      Commit 2613af0e ("virtio_net: migrate mergeable rx buffers to page frag
allocators") changed the mergeable receive buffer size from PAGE_SIZE to
MTU-size, introducing a single-stream regression for benchmarks with large
average packet size. There is no single optimal buffer size for all
workloads.  For workloads with packet size <= MTU bytes, MTU + virtio-net
header-sized buffers are preferred as larger buffers reduce the TCP window
due to SKB truesize. However, single-stream workloads with large average
packet sizes have higher throughput if larger (e.g., PAGE_SIZE) buffers
are used.

This commit auto-tunes the mergeable receiver buffer packet size by
choosing the packet buffer size based on an EWMA of the recent packet
sizes for the receive queue. Packet buffer sizes range from MTU_SIZE +
virtio-net header len to PAGE_SIZE. This improves throughput for
large packet workloads, as any workload with average packet size >=
PAGE_SIZE will use PAGE_SIZE buffers.

These optimizations interact positively with recent commit
ba275241 ("virtio-net: coalesce rx frags when possible during rx"),
which coalesces adjacent RX SKB fragments in virtio_net. The coalescing
optimizations benefit buffers of any size.

Benchmarks taken from an average of 5 netperf 30-second TCP_STREAM runs
between two QEMU VMs on a single physical machine. Each VM has two VCPUs
with all offloads & vhost enabled. All VMs and vhost threads run in a
single 4 CPU cgroup cpuset, using cgroups to ensure that other processes
in the system will not be scheduled on the benchmark CPUs. Trunk includes
SKB rx frag coalescing.

net-next w/ virtio_net before 2613af0e (PAGE_SIZE bufs): 14642.85Gb/s
net-next (MTU-size bufs):  13170.01Gb/s
net-next + auto-tune: 14555.94Gb/s

Jason Wang also reported a throughput increase on mlx4 from 22Gb/s
using MTU-sized buffers to about 26Gb/s using auto-tuning.
Signed-off-by: NMichael Dalton <mwdalton@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      ab7db917
    • M
      virtio-net: use per-receive queue page frag alloc for mergeable bufs · fb51879d
      由 Michael Dalton 提交于 
      The virtio-net driver currently uses netdev_alloc_frag() for GFP_ATOMIC
mergeable rx buffer allocations. This commit migrates virtio-net to use
per-receive queue page frags for GFP_ATOMIC allocation. This change unifies
mergeable rx buffer memory allocation, which now will use skb_refill_frag()
for both atomic and GFP-WAIT buffer allocations.

To address fragmentation concerns, if after buffer allocation there
is too little space left in the page frag to allocate a subsequent
buffer, the remaining space is added to the current allocated buffer
so that the remaining space can be used to store packet data.
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael Dalton <mwdalton@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      fb51879d
    • M
      net: allow > 0 order atomic page alloc in skb_page_frag_refill · 097b4f19
      由 Michael Dalton 提交于 
      skb_page_frag_refill currently permits only order-0 page allocs
unless GFP_WAIT is used. Change skb_page_frag_refill to attempt
higher-order page allocations whether or not GFP_WAIT is used. If
memory cannot be allocated, the allocator will fall back to
successively smaller page allocs (down to order-0 page allocs).

This change brings skb_page_frag_refill in line with the existing
page allocation strategy employed by netdev_alloc_frag, which attempts
higher-order page allocations whether or not GFP_WAIT is set, falling
back to successively lower-order page allocations on failure. Part
of migration of virtio-net to per-receive queue page frag allocators.
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NMichael Dalton <mwdalton@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      097b4f19
    • W
      net_sched: fix error return code in fw_change_attrs() · 722e47d7
      由 Wei Yongjun 提交于 
      The error code was not set if change indev fail, so the error
condition wasn't reflected in the return value. Fix to return a
negative error code from this error handling case instead of 0.

Fixes: 2519a602 ('net_sched: optimize tcf_match_indev()')
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      722e47d7