Sorry. The performance tested by iperf is degraded from 4.5 Gbps to 750Mbps per flow.
Harold Huang <baymaxhu...@gmail.com> 于2022年2月23日周三 21:13写道： > > I see in dpdk virtio-user driver, the TUNSETSNDBUF is initialized with > INT_MAX, see: > https://github.com/DPDK/dpdk/blob/main/drivers/net/virtio/virtio_user/vhost_kernel_tap.c#L169 > It is ok because tap driver uses it to support tx baching, see this > patch: > https://github.com/torvalds/linux/commit/0a0be13b8fe2cac11da2063fb03f0f39359b3069 > > But in tun_xdp_one, napi is not supported and I want to user napi in > tun_get_user to enable gro. As I result, I change the sndbuf to a > value such as 212992 in /proc/sys/net/core/wmem_default. But the > performance tested by iperf is greatly degraded, from 4.5 Gbps to > 750Gbps per flow. I see the the iperf server consume 100% cpu core, > which should be the bottleneck of the this test. The perf top result > of iperf server cpu core is as follows: > > ''' > Samples: 72 of event 'cycles', 4000 Hz, Event count (approx.): > 22685278 lost: 0/0 drop: 0/0 > Overhead Shared O Symbol > 59.86% [kernel] [k] report_bug > 20.66% [kernel] [k] module_find_bug > 6.51% [kernel] [k] common_interrupt > 2.82% [kernel] [k] __slab_free > 1.48% [kernel] [k] copy_user_enhanced_fast_string > 1.44% [kernel] [k] __skb_datagram_iter > 1.42% [kernel] [k] notifier_call_chain > 1.41% [kernel] [k] irq_work_run_list > 1.41% [kernel] [k] update_irq_load_avg > 1.41% [kernel] [k] task_tick_fair > 1.41% [kernel] [k] cmp_ex_search > 0.16% [kernel] [k] __ghes_peek_estatus.isra.12 > 0.02% [kernel] [k] acpi_os_read_memory > 0.00% [kernel] [k] native_apic_mem_write > ''' > I am not clear about the test result. Can we change the sndbuf size in > dpdk? Is any way to enable vhost_net to use napi without changing the > tun kernel driver?
