On Thu, Jan 29, 2026 at 5:20 AM Vishwanath Seshagiri <[email protected]> wrote: > > Introduce page_pool support in virtio_net driver to enable page recycling > in RX buffer allocation and avoid repeated page allocator calls. This > applies to mergeable and small buffer modes. > > Beyond performance improvements, this patch is a prerequisite for enabling > memory provider-based zero-copy features in virtio_net, specifically devmem > TCP and io_uring ZCRX, which require drivers to use page_pool for buffer > management. > > The implementation preserves the DMA premapping optimization introduced in > commit 31f3cd4e5756 ("virtio-net: rq submits premapped per-buffer") by > conditionally using PP_FLAG_DMA_MAP when the virtio backend supports > standard DMA API (vhost, virtio-pci), and falling back to allocation-only > mode for backends with custom DMA mechanisms (VDUSE). > > Changes in v2 > ============= > > Addressing reviewer feedback from v1: > > - Add "select PAGE_POOL" to Kconfig (Jason Wang) > - Move page pool creation from ndo_open to probe for device lifetime > management (Xuan Zhuo, Jason Wang) > - Implement conditional DMA strategy using virtqueue_dma_dev(): > - When non-NULL: use PP_FLAG_DMA_MAP for page_pool-managed DMA premapping > - When NULL (VDUSE): page_pool handles allocation only > - Use page_pool_get_dma_addr() + virtqueue_add_inbuf_premapped() to > preserve DMA premapping optimization from commit 31f3cd4e5756 > ("virtio-net: rq submits premapped per-buffer") (Jason Wang) > - Remove dual allocation code paths - page_pool now always used for > small/mergeable modes (Jason Wang) > - Remove unused virtnet_rq_alloc/virtnet_rq_init_one_sg functions > - Add comprehensive performance data (Michael S. Tsirkin) > - v1 link: > https://lore.kernel.org/virtualization/[email protected]/ > > Performance Results > =================== > > Tested using iperf3 TCP_STREAM with virtio-net on vhost backend. > 300-second runs, results show throughput and TCP retransmissions. > The base kernel is synced to net tree and commit: 709bbb015538. > > Mergeable Buffer Mode (mrg_rxbuf=on, GSO enabled, MTU 1500): > +--------+---------+---------+------------+------------+--------+--------+ > | Queues | Streams | Patch | Throughput | Retries | Delta | Retry% | > +--------+---------+---------+------------+------------+--------+--------+ > | 1 | 1 | base | 25.7 Gbps | 0 | - | - | > | 1 | 1 | pp | 26.2 Gbps | 0 | +1.9% | 0% | > +--------+---------+---------+------------+------------+--------+--------+ > | 8 | 8 | base | 95.6 Gbps | 236,432 | - | - | > | 8 | 8 | pp | 97.9 Gbps | 188,249 | +2.4% | -20.4% | > +--------+---------+---------+------------+------------+--------+--------+ > > Small Buffer Mode (mrg_rxbuf=off, GSO disabled, MTU 1500): > +--------+---------+---------+------------+------------+--------+--------+ > | Queues | Streams | Patch | Throughput | Retries | Delta | Retry% | > +--------+---------+---------+------------+------------+--------+--------+ > | 1 | 1 | base | 9.17 Gbps | 15,152 | - | - | > | 1 | 1 | pp | 9.19 Gbps | 12,203 | +0.2% | -19.5% | > +--------+---------+---------+------------+------------+--------+--------+ > | 8 | 8 | base | 43.0 Gbps | 974,500 | - | - | > | 8 | 8 | pp | 44.7 Gbps | 717,411 | +4.0% | -26.4% | > +--------+---------+---------+------------+------------+--------+--------+
It would be better to have more benchmark like: PPS (using pktgen on host and XDP_DROP in the guest) We can see PPS as well as XDP performance as well. Thanks > > Testing > ======= > > The patches have been tested with: > - iperf3 bulk transfer workloads (multiple queue/stream configurations) > - Included selftests for buffer circulation verification > - Edge case testing: device unbind/bind cycles, rapid interface open/close, > traffic during close, ethtool feature toggling, close with pending refill > work, and data integrity verification > > Vishwanath Seshagiri (2): > virtio_net: add page_pool support for buffer allocation > selftests: virtio_net: add buffer circulation test > > drivers/net/Kconfig | 1 + > drivers/net/virtio_net.c | 353 ++++++++++-------- > .../drivers/net/virtio_net/basic_features.sh | 70 ++++ > 3 files changed, 273 insertions(+), 151 deletions(-) > > -- > 2.47.3 >
