From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gandalf.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) by passt.top (Postfix) with ESMTPS id 5AE165A0082 for ; Wed, 25 Jan 2023 07:24:03 +0100 (CET) Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4P1v1W1f5nz4xwp; Wed, 25 Jan 2023 17:23:59 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=201602; t=1674627839; bh=LDGJxvGjzkUNEtNp50txQQ8fUwG86ovpIPO33LgiiAk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qFPFqu1vvCqY8PJ6aHOZKXhxy2NUCrRxZQDBa+yfxh1ri5Mdd4QTdcN6kv5MqVW2k t5w5rFGkZcXCB5WtQhOWdyPMHtmrjJ2q88y9nX0A1ui1ihrC31DbyYKjEyhNGM73Tt dQHxAyfk1j1bPV1e7bMGXJyzB8ueenhtLcHcKwyE= Date: Wed, 25 Jan 2023 14:13:44 +1100 From: David Gibson To: Stefano Brivio Subject: Re: [PATCH v3 00/18] RFC: Unify and simplify tap send path Message-ID: References: <20230106004322.985665-1-david@gibson.dropbear.id.au> <20230124222043.281ef58c@elisabeth> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="G1IRrO343veB+kL9" Content-Disposition: inline In-Reply-To: <20230124222043.281ef58c@elisabeth> Message-ID-Hash: RKL7XWNOJRFHNB3NV36WLHKJUJPHJALP X-Message-ID-Hash: RKL7XWNOJRFHNB3NV36WLHKJUJPHJALP 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: --G1IRrO343veB+kL9 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jan 24, 2023 at 10:20:43PM +0100, Stefano Brivio wrote: > On Fri, 6 Jan 2023 11:43:04 +1100 > David Gibson wrote: >=20 > > Although we have an abstraction for the "slow path" (DHCP, NDP) guest > > bound packets, the TCP and UDP forwarding paths write directly to the > > tap fd. However, it turns out how they send frames to the tap device > > is more similar than it originally appears. > >=20 > > This series unifies the low-level tap send functions for TCP and UDP, > > and makes some clean ups along the way. > >=20 > > This is based on my earlier outstanding series. >=20 > For some reason, performance tests consistently get stuck (both TCP and > UDP, sometimes throughput, sometimes latency tests) with this series, > and not without it, but I don't see any possible relationship with that. Drat, I didn't encounter that. Any chance you could bisect to figure out which patch specifically seems to trigger it? I wonder if this could be related to the stalls I'm debugging, although those didn't appear on the perf tests and also occur on main. I have now discovered they seem to be masked by large socket buffer sizes - more info at https://bugs.passt.top/show_bug.cgi?id=3D41 > I checked debug output and I couldn't find anything obviously wrong > there. I just started checking packet captures now... Hrm, probably not then. The stalls I'm seeing are associated with lots of partial sends. --=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 --G1IRrO343veB+kL9 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEoULxWu4/Ws0dB+XtgypY4gEwYSIFAmPQnl8ACgkQgypY4gEw YSKCuQ//d8kBat540R8PlfJUy5CCquFsJKSTQ+eBdmCuu6tZetpXf6NAVM5pZ6l2 OoaJmHmOVuwOaYJez0w5A6OvPzTTolazNrE1Hj85q7ZgjzB/fjWU9g2fNHQmIYF2 pPqaT3hu/RPtW6uHWTJR81qoN90Ob47nQF5KugxMntDuo/8gOjvDKIvASbfmf4q+ QPCwp1QjkkAFOHWZKz6+deIXcqUBRmv2gZbZC4YWuFk9U/vWXL3UMmbJZ+98JBwg 7m+vZzlOxc+gByEJBl+k2baWcnk8Nva5i5qerYXGzhLQghcqSJzPgFUO/ycsnnZO yG7n6nPAghz4JtJmADWNjLZ3skv71D6IVeJ1mQ4C/xLfNrbiMBwYjKHs3hEAlWn6 /ivR+nTj+nOgzquqs2Q7SaI3knY7q4pE8lKGjYcR846Vv2bJeWuCoJhYjGNvNs8H ycVPJtbwkLSnVIsnEwqeD15V10ZAdEVaYCDOySwF0zySnxTTMFxHqiA+ASmRwH1l 6ikUFlzzjF03mKFURkdJ9kOsG9A9W0Iv4M/IF5BJDleERKzUXPAotEW4pY/xue3c yKQSgV358GGzbgYi63m03lAyxeqHjioXjYf3hBbSVT+//YDqojR/aToBqEJwfCO+ 92BLlFgqoIF9OBGP9eJ+S8go3+y90tjLzE+Aa27no82ne059D60= =hqUU -----END PGP SIGNATURE----- --G1IRrO343veB+kL9--