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Fri, 02 Oct 2026 03:39:08 -0700 (PDT) Date: Fri, 2 Oct 2026 12:39:03 +0200 From: Stefano Garzarella To: physicalmtea@gmail.com Cc: stefanha@redhat.com, mst@redhat.com, jasowangio@gmail.com, eperezma@redhat.com, xuanzhuo@linux.alibaba.com, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, virtualization@lists.linux.dev, kvm@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/5] vsock: reduce RX per-packet socket overhead Message-ID: References: <20261002074551.318789-1-physicalmtea@gmail.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20261002074551.318789-1-physicalmtea@gmail.com> On Fri, Oct 02, 2026 at 07:45:46AM +0000, physicalmtea@gmail.com wrote: >From: Jia Jia > >This series reduces per-packet socket overhead in the virtio-vsock RX >worker. I did a quick look but IMO this is hard to review, please try to keep patches as small as possible, e.g. where you are introducing ctx, store ctx->net in a net variable, so you don't need to touch the entire function, etc. Please check https://docs.kernel.org/process/coding-assistants.html and also https://docs.kernel.org/process/submitting-patches.html ans also https://docs.kernel.org/process/maintainer-netdev.html#git-trees-and-patch-flow (I guess this is net-next material). I don't think this series was sent properly, I tried `b4 am 20261002074551.318789-1-physicalmtea@gmail.com` without success and also looking at https://lore.kernel.org/virtualization/20261002074551.318789-1-physicalmtea@gmail.com/ I can't see the full series, please check your workflow. Also, is this for vsock core or just virtio-vsock? if it's just virtio-vsock transports, please use "vsock/virtio" prefix. > >Patch 1: separate socket lookup from locked packet processing. > >Patch 2: keep one socket lock across a bounded run of established >STREAM/RW packets for the same native socket. > >Patch 3: reuse the locked socket for later packets with the same >address tuple. > >Patch 4: coalesce default write-space notifications while that >lock is held. > >Patch 5: defer the default readable callback until after the batch >unlocks. Custom callbacks retain per-packet notification behavior. > >Performance: > >Tested on single-stream AF_VSOCK (1 reader on Guest CPU0, virtio-vsock IRQ >on Guest CPU1, fresh QEMU guest per state, 16 balanced AB/BA pairs per >payload). What the host is using? vhost-vsock? > >End-to-end RX throughput (64K receiver buffer, SO_RCVLOWAT=1): > > payload baseline RX (G/s) PATCH RX (G/s) throughput change (95% CI) What G is? Gbit? Gbytes? > 256B 0.5722 1.0286 +79.76% [+75.40%, +84.23%] > 512B 1.1464 1.9779 +72.53% [+69.50%, +75.63%] > 1K 2.2714 3.6368 +60.12% [+56.92%, +63.37%] > 4K 3.9095 7.7160 +97.37% [+92.09%, +102.79%] Why stop to 4k? > >Fixed-syscall stress test (receiver buffer = sender write size; RX in G/s): > > payload baseline RX PATCH RX throughput change (95% CI) recv() base/patch > 256B 0.2885 0.6737 +133.50% [+123.58%, +143.86%] 1048577/1048577 > 512B 0.5631 1.2091 +114.71% [+104.97%, +124.92%] 1048577/1048577 > 1K 1.5361 2.9678 +93.20% [+80.15%, +107.20%] 1048577/1048577 > 4K 2.8378 6.1878 +118.05% [+109.15%, +127.33%] 538802/525645 > >Request-response latency (Ping-Pong RTT, 10,000 requests): What tool did you used for both throughput and latency? > > payload baseline mean RTT (us) PATCH mean RTT (us) change (95% CI) > 256B 126.968 124.541 -1.91% [-3.35%, -0.45%] > 4K 130.362 126.664 -2.84% [-5.12%, -0.50%] Whys only this payload cases? For latency we should use even try small payloads IMO like 64 bytes. Thanks, Stefano > >Diagnostic Guest CPU1 system-wide cycles (fixed-64K receiver, with perf): > > Buffer size baseline cycles/B PATCH cycles/B cycles change (95% CI) > 256B 15.287 13.630 -10.84% [-12.51%, -9.14%] > 512B 7.306 6.611 -9.51% [-10.92%, -8.08%] > 1K 3.811 3.458 -9.25% [-10.96%, -7.50%] > 4K 1.850 1.669 -9.75% [-11.78%, -7.67%] > >Jia Jia (5): > vsock: split socket lookup from locked RX processing > vsock: amortize RX socket locking for stream packets > vsock: reuse same-flow socket lookup in RX batches > vsock: coalesce RX write-space notifications in lock batches > vsock: defer RX readable notifications until batch unlock > > include/linux/virtio_vsock.h | 14 ++ > include/net/af_vsock.h | 3 + > net/vmw_vsock/af_vsock.c | 2 + > net/vmw_vsock/virtio_transport.c | 48 ++++- > net/vmw_vsock/virtio_transport_common.c | 341 +++++++++++++++++++++++++++----- > 5 files changed, 357 insertions(+), 51 deletions(-) > >base-commit: f5f84daefcd92d7a630066635ecea1433ed5eac7 >-- >2.53.0 >