From: Stefano Brivio <sbrivio@redhat.com>
To: passt-dev@passt.top
Cc: David Gibson <david@gibson.dropbear.id.au>,
Laurent Vivier <lvivier@redhat.com>
Subject: Re: [PATCH v2 4/5] tcp, udp: Pad batched frames to 60 bytes (802.3 minimum) in non-vhost-user modes
Date: Fri, 5 Dec 2025 06:48:42 +0100 [thread overview]
Message-ID: <20251205064842.42abd0d5@elisabeth> (raw)
In-Reply-To: <20251205005157.2577523-5-sbrivio@redhat.com>
On Fri, 5 Dec 2025 01:51:56 +0100
Stefano Brivio <sbrivio@redhat.com> wrote:
> Add a further iovec frame part, TCP_IOV_ETH_PAD for TCP and
> UDP_IOV_ETH_PAD for UDP, after the payload, make that point to a
> zero-filled buffer, and send out a part of it if needed to reach
> the minimum frame length given by 802.3, that is, 60 bytes altogether.
>
> The frames we might need to pad are IPv4 only (the IPv6 header is
> larger), and are typically TCP ACK segments but can also be small
> data segments or datagrams.
>
> Link: https://bugs.passt.top/show_bug.cgi?id=166
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> Reviewed-by: Laurent Vivier <lvivier@redhat.com>
...for some reason, in combination with the previous series with TCP
throughput fixes, this patch now seems to break basic transfers ("large
transfer", IPv4, guest to host), with passt only.
I'm fairly sure it didn't cause failures when I ran tests on this
series alone, at least twice, once now and once for the RFC version, but
it might also be that I missed running tests (in isolation) for some
reason.
No idea where the issue is, yet...
--
Stefano
next prev parent reply other threads:[~2025-12-05 5:48 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-05 0:51 [PATCH v2 0/5] Pad all inbound frames to 802.3 minimum size if needed Stefano Brivio
2025-12-05 0:51 ` [PATCH v2 1/5] tap: Pad non-batched frames to 802.3 minimum (60 bytes) " Stefano Brivio
2025-12-05 3:23 ` David Gibson
2025-12-05 0:51 ` [PATCH v2 2/5] tcp: Fix coding style for comment to enum tcp_iov_parts Stefano Brivio
2025-12-05 0:51 ` [PATCH v2 3/5] udp: Fix coding style for comment to enum udp_iov_idx Stefano Brivio
2025-12-05 0:51 ` [PATCH v2 4/5] tcp, udp: Pad batched frames to 60 bytes (802.3 minimum) in non-vhost-user modes Stefano Brivio
2025-12-05 5:48 ` Stefano Brivio [this message]
2025-12-05 11:27 ` Stefano Brivio
2025-12-05 0:51 ` [PATCH v2 5/5] tcp, udp: Pad batched frames for vhost-user modes to 60 bytes (802.3 minimum) Stefano Brivio
2025-12-05 4:07 ` David Gibson
2025-12-06 1:26 ` Stefano Brivio
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