From: Bui Quang Minh <minhquangbui99@gmail.com>
To: "Michael S. Tsirkin" <mst@redhat.com>,
Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: "Jason Wang" <jasowang@redhat.com>,
netdev@vger.kernel.org, "Eugenio Pérez" <eperezma@redhat.com>,
"Andrew Lunn" <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
"Eric Dumazet" <edumazet@google.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Paolo Abeni" <pabeni@redhat.com>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Jesper Dangaard Brouer" <hawk@kernel.org>,
"John Fastabend" <john.fastabend@gmail.com>,
"Stanislav Fomichev" <sdf@fomichev.me>,
virtualization@lists.linux.dev, linux-kernel@vger.kernel.org,
bpf@vger.kernel.org
Subject: Re: [PATCH net 1/3] virtio-net: make refill work a per receive queue work
Date: Wed, 24 Dec 2025 23:49:59 +0700 [thread overview]
Message-ID: <75e32d60-51b1-4c46-bd43-d17af7440e74@gmail.com> (raw)
In-Reply-To: <20251223204555-mutt-send-email-mst@kernel.org>
On 12/24/25 08:47, Michael S. Tsirkin wrote:
> On Wed, Dec 24, 2025 at 09:37:14AM +0800, Xuan Zhuo wrote:
>> Hi Jason,
>>
>> I'm wondering why we even need this refill work. Why not simply let NAPI retry
>> the refill on its next run if the refill fails? That would seem much simpler.
>> This refill work complicates maintenance and often introduces a lot of
>> concurrency issues and races.
>>
>> Thanks.
> refill work can refill from GFP_KERNEL, napi only from ATOMIC.
>
> And if GFP_ATOMIC failed, aggressively retrying might not be a great idea.
>
> Not saying refill work is a great hack, but that is the reason for it.
In case no allocated received buffer and NAPI refill fails, the host
will not send any packets. If there is no busy polling loop either, the
RX will be stuck. That's also the reason why we need refill work. Is it
correct?
Thanks,
Quang Minh.
next prev parent reply other threads:[~2025-12-24 16:50 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-23 15:25 [PATCH net 0/3] virtio-net: fix the deadlock when disabling rx NAPI Bui Quang Minh
2025-12-23 15:25 ` [PATCH net 1/3] virtio-net: make refill work a per receive queue work Bui Quang Minh
2025-12-24 0:52 ` Jason Wang
2025-12-24 1:37 ` Xuan Zhuo
2025-12-24 1:47 ` Michael S. Tsirkin
2025-12-24 16:49 ` Bui Quang Minh [this message]
2025-12-25 15:55 ` Bui Quang Minh
2025-12-25 16:27 ` Michael S. Tsirkin
2025-12-25 7:33 ` Jason Wang
2025-12-25 16:27 ` Michael S. Tsirkin
2025-12-26 1:31 ` Jason Wang
2025-12-26 7:37 ` Michael S. Tsirkin
2025-12-29 2:57 ` Jason Wang
2025-12-30 16:28 ` Bui Quang Minh
2025-12-30 16:44 ` Michael S. Tsirkin
2025-12-31 7:30 ` Jason Wang
2025-12-31 15:25 ` Bui Quang Minh
2025-12-24 16:43 ` Bui Quang Minh
2025-12-24 1:34 ` Michael S. Tsirkin
2025-12-24 10:19 ` Michael S. Tsirkin
2025-12-24 17:03 ` Bui Quang Minh
2025-12-23 15:25 ` [PATCH net 2/3] virtio-net: ensure rx NAPI is enabled before enabling refill work Bui Quang Minh
2025-12-24 1:45 ` Michael S. Tsirkin
2025-12-24 17:49 ` Bui Quang Minh
2025-12-24 10:20 ` Michael S. Tsirkin
2025-12-23 15:25 ` [PATCH net 3/3] virtio-net: schedule the pending refill work after being enabled Bui Quang Minh
2025-12-24 10:17 ` Michael S. Tsirkin
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