From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gandalf.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) by passt.top (Postfix) with ESMTPS id 282285A005E for ; Wed, 14 Dec 2022 02:47:36 +0100 (CET) Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4NWyst3JZ9z4xvR; Wed, 14 Dec 2022 12:47:30 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=201602; t=1670982450; bh=267qLbJu4YwoGYlg+hF9lDIS5Orm9ZBUiR5dsWh/UWQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=H6IwX7+UnVDthRio2gFw5CAyGKfGonuFOIE92NLllYGtVNNSbAdK3xZOQFOIaP/bV 4eKIxG2HvOiPIt2+SmSxP4LAfpA2iCKPh8oa0POrx1RAJAmMU29GiF3Z02gPjBNgTA LJQR+Kc7RtLC4InthJGrZX6kqfwNh4RA3STaZhn4= Date: Wed, 14 Dec 2022 12:42:14 +1100 From: David Gibson To: Stefano Brivio Subject: Re: [PATCH 4/8] udp: Receive multiple datagrams at once on the pasta sock->tap path Message-ID: References: <20221205081425.2614425-1-david@gibson.dropbear.id.au> <20221205081425.2614425-5-david@gibson.dropbear.id.au> <20221213234847.6c723ad9@elisabeth> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="aRthg5mTgrOVK9Xs" Content-Disposition: inline In-Reply-To: <20221213234847.6c723ad9@elisabeth> Message-ID-Hash: QAHHKSYDT3COUFFYJW3K45IFUAQ2RKVS X-Message-ID-Hash: QAHHKSYDT3COUFFYJW3K45IFUAQ2RKVS 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 X-Mailman-Version: 3.3.3 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: --aRthg5mTgrOVK9Xs Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Dec 13, 2022 at 11:48:47PM +0100, Stefano Brivio wrote: > Sorry for the long delay here, >=20 > On Mon, 5 Dec 2022 19:14:21 +1100 > David Gibson wrote: >=20 > > Usually udp_sock_handler() will receive and forward multiple (up to 32) > > datagrams in udp_sock_handler(), then forward them all to the tap > > interface. For unclear reasons, though, when in pasta mode we will only > > receive and forward a single datagram at a time. Change it to receive > > multiple datagrams at once, like the other paths. >=20 > This is explained in the commit message of 6c931118643c ("tcp, udp: > Receive batching doesn't pay off when writing single frames to tap"). >=20 > I think it's worth re-checking the throughput now as this path is a bit > different, but unfortunately I didn't include this in the "perf" tests :( > because at the time I introduced those I wasn't sure it even made sense to > have traffic from the same host being directed to the tap device. >=20 > The iperf3 runs were I observed this are actually the ones from the Podman > demo. Ideally that case should be also checked in the perf/pasta_udp test= s. Hm, ok. > How fundamental is this for the rest of the series? I couldn't find any > actual dependency on this but I might be missing something. So the issue is that prior to this change in pasta we receive multiple frames at once on the splice path, but one frame at a time on the tap path. By the end of this series we can't do that any more, because we don't know before the recvmmsg() which one we'll be doing. --=20 David Gibson | 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 --aRthg5mTgrOVK9Xs Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEoULxWu4/Ws0dB+XtgypY4gEwYSIFAmOZKe8ACgkQgypY4gEw YSLzbxAAi0oprJXNu9eBdc7lcSJprAhG1iW9bQaYrzB4humupaxm+zs/tibWRMW9 VbJeIDtMUp4qbZ8OwcI2OCxlwIL4oXSCJ9eozM7gTY5UY8NJk2at1ZzZWGInHpOw sGzsV0FQqmRBNZ+AGW5Ymy5tfLEtCNus2uf7Xc4Ty4dzTXgSDSWR+On1xHhwTJO/ legX5mUwvNaAkQ/LJv/cxS3tBTBUGgNYMnYasvlBKAje0lIH98zHyC/Nk7w3MMjz 44MdOiEzHGNAShwMfgDD225DRuc5mtErJ8xaZhq7IZ4IkMSgvnEeVWqeujSqnecB wosW8pdTWKAnxzUtEboVH9mo8KDZfcVE2gbXJSlMHT+Rx0cD2cYcNjnWq33nHdrn TwNOQCHrgbQI2uL+WzMhbge56hev9aWZpo5qL68ykSm1dOXK2g4mE+RAfgXJtgpz W3olb5cyDIxZvTzezmfw6QB3fYrnPcY2xWQCXv4QW3N2LYdxVnXL7WcsUKidbOw3 S+9f7gsOwfENw1cjjrS7FQQIXBOEDzvaG11wbtsK0FzwuBwPk3oYm9O12zdLyTuc cMH4gVFH69tUs1FqSwYVYkCTBxSbvqUNAzhpUFcXEsrsNaGIk5Kh+8KaXH/YRAy4 31+cKGYhGqaxLlx9MV/mcXQNS0qASHscTJITgrxg1/dbE+sh308= =QW3T -----END PGP SIGNATURE----- --aRthg5mTgrOVK9Xs--