On 09/18/2017 03:36 AM, Jason Wang wrote: > > > On 2017年09月18日 11:13, Jason Wang wrote: >> >> >> On 2017年09月16日 03:19, Matthew Rosato wrote: >>>> It looks like vhost is slowed down for some reason which leads to more >>>> idle time on 4.13+VHOST_RX_BATCH=1. Appreciated if you can collect the >>>> perf.diff on host, one for rx and one for tx. >>>> >>> perf data below for the associated vhost threads, baseline=4.12, >>> delta1=4.13, delta2=4.13+VHOST_RX_BATCH=1 >>> >>> Client vhost: >>> >>> 60.12% -11.11% -12.34% [kernel.vmlinux] [k] raw_copy_from_user >>> 13.76% -1.28% -0.74% [kernel.vmlinux] [k] get_page_from_freelist >>> 2.00% +3.69% +3.54% [kernel.vmlinux] [k] __wake_up_sync_key >>> 1.19% +0.60% +0.66% [kernel.vmlinux] [k] __alloc_pages_nodemask >>> 1.12% +0.76% +0.86% [kernel.vmlinux] [k] copy_page_from_iter >>> 1.09% +0.28% +0.35% [vhost] [k] vhost_get_vq_desc >>> 1.07% +0.31% +0.26% [kernel.vmlinux] [k] alloc_skb_with_frags >>> 0.94% +0.42% +0.65% [kernel.vmlinux] [k] alloc_pages_current >>> 0.91% -0.19% -0.18% [kernel.vmlinux] [k] memcpy >>> 0.88% +0.26% +0.30% [kernel.vmlinux] [k] __next_zones_zonelist >>> 0.85% +0.05% +0.12% [kernel.vmlinux] [k] iov_iter_advance >>> 0.79% +0.09% +0.19% [vhost] [k] __vhost_add_used_n >>> 0.74% [kernel.vmlinux] [k] get_task_policy.part.7 >>> 0.74% -0.01% -0.05% [kernel.vmlinux] [k] tun_net_xmit >>> 0.60% +0.17% +0.33% [kernel.vmlinux] [k] policy_nodemask >>> 0.58% -0.15% -0.12% [ebtables] [k] ebt_do_table >>> 0.52% -0.25% -0.22% [kernel.vmlinux] [k] __alloc_skb >>> ... >>> 0.42% +0.58% +0.59% [kernel.vmlinux] [k] eventfd_signal >>> ... >>> 0.32% +0.96% +0.93% [kernel.vmlinux] [k] finish_task_switch >>> ... >>> +1.50% +1.16% [kernel.vmlinux] [k] get_task_policy.part.9 >>> +0.40% +0.42% [kernel.vmlinux] [k] __skb_get_hash_symmetr >>> +0.39% +0.40% [kernel.vmlinux] [k] _copy_from_iter_full >>> +0.24% +0.23% [vhost_net] [k] vhost_net_buf_peek >>> >>> Server vhost: >>> >>> 61.93% -10.72% -10.91% [kernel.vmlinux] [k] raw_copy_to_user >>> 9.25% +0.47% +0.86% [kernel.vmlinux] [k] free_hot_cold_page >>> 5.16% +1.41% +1.57% [vhost] [k] vhost_get_vq_desc >>> 5.12% -3.81% -3.78% [kernel.vmlinux] [k] skb_release_data >>> 3.30% +0.42% +0.55% [kernel.vmlinux] [k] raw_copy_from_user >>> 1.29% +2.20% +2.28% [kernel.vmlinux] [k] copy_page_to_iter >>> 1.24% +1.65% +0.45% [vhost_net] [k] handle_rx >>> 1.08% +3.03% +2.85% [kernel.vmlinux] [k] __wake_up_sync_key >>> 0.96% +0.70% +1.10% [vhost] [k] translate_desc >>> 0.69% -0.20% -0.22% [kernel.vmlinux] [k] tun_do_read.part.10 >>> 0.69% [kernel.vmlinux] [k] tun_peek_len >>> 0.67% +0.75% +0.78% [kernel.vmlinux] [k] eventfd_signal >>> 0.52% +0.96% +0.98% [kernel.vmlinux] [k] finish_task_switch >>> 0.50% +0.05% +0.09% [vhost] [k] vhost_add_used_n >>> ... >>> +0.63% +0.58% [vhost_net] [k] vhost_net_buf_peek >>> +0.32% +0.32% [kernel.vmlinux] [k] _copy_to_iter >>> +0.19% +0.19% [kernel.vmlinux] [k] __skb_get_hash_symmetr >>> +0.11% +0.21% [vhost] [k] vhost_umem_interval_tr >>> >> >> Looks like for some unknown reason which leads more wakeups. >> >> Could you please try to attached patch to see if it solves or mitigate >> the issue? >> >> Thanks > > My bad, please try this. > > Thanks
Thanks Jason. Built 4.13 + supplied patch, I see some decrease in wakeups, but there's still quite a bit more compared to 4.12 (baseline=4.12, delta1=4.13, delta2=4.13+patch): client: 2.00% +3.69% +2.55% [kernel.vmlinux] [k] __wake_up_sync_key server: 1.08% +3.03% +1.85% [kernel.vmlinux] [k] __wake_up_sync_key Throughput was roughly equivalent to base 4.13 (so, still seeing the regression w/ this patch applied).
