From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: passt.top; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: passt.top; dkim=pass (2048-bit key; secure) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.a=rsa-sha256 header.s=202510 header.b=AFwl+qLK; dkim-atps=neutral Received: from mail.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) by passt.top (Postfix) with ESMTPS id 70FC05A061B for ; Fri, 05 Dec 2025 03:37:05 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=202510; t=1764902221; bh=PIgm7OA+w8OD+wCbwi91p+yecYQHWyM4IeNftn0DtnE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=AFwl+qLKc0kcE40RUw8mudgangR5CVgCbm5vfjwPHTfYU3phLJF1qezZFWyfHFiN1 7VNHvnPxM37wD6umvLYgT2DAaFm09rtol733eth2N3AT6H2G2ok380AXP1Q68VN+oq A0e/7VR8QVZpEV0mgf4ZT50g0QcTdI82XLHAwcIdUgAEV/Xhs8YhThcgZt83Q3jrSB iFOA3n6r5G22TbJbABg1RHtybe9wJS4oNigARwibvj/ZPHPMleqZIwE16FLRAaoFSF eAeMvWsXvEOU1zqaQByWDaVWelKdsABXHblEcbeKtuok/qIt4XU7KV/2aF7vXfT8tq ZC7Wi9zI09vCw== Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4dMwWK3dGxz4wGX; Fri, 05 Dec 2025 13:37:01 +1100 (AEDT) Date: Fri, 5 Dec 2025 13:35:50 +1100 From: David Gibson To: Stefano Brivio Subject: Re: [PATCH 7/8] tcp: Send a duplicate ACK also on complete sendmsg() failure Message-ID: References: <20251204074542.2156548-1-sbrivio@redhat.com> <20251204074542.2156548-8-sbrivio@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="xgJWW46SyzfTNGBv" Content-Disposition: inline In-Reply-To: <20251204074542.2156548-8-sbrivio@redhat.com> Message-ID-Hash: 3JIBHMX5I6E3UPGMAFAJDPOVVBKNZECQ X-Message-ID-Hash: 3JIBHMX5I6E3UPGMAFAJDPOVVBKNZECQ X-MailFrom: dgibson@gandalf.ozlabs.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: passt-dev@passt.top, Max Chernoff X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --xgJWW46SyzfTNGBv Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Dec 04, 2025 at 08:45:40AM +0100, Stefano Brivio wrote: > ...in order to trigger a fast retransmit as soon as possible. There's > no benefit in forcing the sender to wait for a longer time than that. >=20 > We already do this on partial failures (short socket writes), but for > historical reason not on complete failures. Make these two cases > consistent between each other. >=20 > Signed-off-by: Stefano Brivio Reviewed-by: David Gibson > --- > tcp.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) >=20 > diff --git a/tcp.c b/tcp.c > index 454df69..76a9daf 100644 > --- a/tcp.c > +++ b/tcp.c > @@ -1965,7 +1965,7 @@ eintr: > goto eintr; > =20 > if (errno =3D=3D EAGAIN || errno =3D=3D EWOULDBLOCK) { > - tcp_send_flag(c, conn, ACK_IF_NEEDED); > + tcp_send_flag(c, conn, ACK | DUP_ACK); > return p->count - idx; > =20 > } > --=20 > 2.43.0 >=20 --=20 David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson --xgJWW46SyzfTNGBv Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEO+dNsU4E3yXUXRK2zQJF27ox2GcFAmkyRQUACgkQzQJF27ox 2GcczA/8CYm1FYL6h8A5uHFfBWx2zTSdFwA9AdgkKhRoMeDkX/Fyf8h3JOd/cMtH Ic5UXe6M2uB/Yv8BdSRp0+Kc6Mf7jwL0MCguN1GHlYpweRpFmCd0U4NZHacqONhj hxe2ds5gBaLA/zcHDZ7/SnIo0SyRxjxBqozFoNIvNuxGKWKkMKBj3C8ucgGyQQ+3 mtJekAsZ99+rj16Fvmx/FzkFu4iwEeCD5OguBpPFlnfURIC5f0roZw5dQRvnj61C Cv85b6smBxxpW8Q23BCs6QvhBSHGfcV700RWq7sks3oHnr8i21KJYWyf5sxEIgMu 74qYWl9iX00NZkYGV4245jv7Ej00RyLs3y3L9FtC5V+7vNVuollYllIUHnOshuV3 5xsH9LWwASnoTG6WN44vGX6rqwtBOarM9wXJIjc/CdHBQg/gq2npEr8RjU466a5V Xomv/w9bnd0T9/zQxa5GOqBM4G6dnrMZMSlAySiL+4dG6astWZ5DskpkGh5Ys06D 8F3qVV4Ma5Dh5dtaVXqabIh75IETXq7mpkQQLs/i3VSdldgTMagY0NYjHhmyDWip ux+kmxRmpnfICPfPOT+Y9YrlnJCsImbW7oTcpDsDGGWwQLFsNzMTVoAlfgAttuQw st6PZVJnh7CTbLsofnpDkKcBL1ZYTZApqgbGdngoDbxuJJ6T0xI= =b+Yw -----END PGP SIGNATURE----- --xgJWW46SyzfTNGBv--