From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) by passt.top (Postfix) with ESMTPS id 127705A004E for ; Wed, 24 Jul 2024 05:37:29 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=202312; t=1721792242; bh=qi4v+TMORtNISmg25175jv8eslG5le+XUVRLPRm5Qpc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MkxdnNu2yJchZDCSU64sjpYxqvaj675/N4dxhHRhMahVRCIr7A8vVOdbkwXFjcDRE P+wSpAxHRCDIHvpVpSK4d9lEZnEHqoBHhwgE06+Jh/msfjti5HIOYYCRwPyTU/DywT 1laEbluO3unoRxc30kH5sqb22HrHNtsouYkl0z8+AFeD3LnHPyPs9/t9aZLiMHIT5Y ZaoR6ecQDkOH8mG+rn1fox06lyu/2/c4UwvL4eTSGGuEP4g43X9QD2CFwPsc2E2Ifu hGb8QKBwtFGwO08doBYb5mbAB0SMeq2BD1dE2JYFeaPkSmTybhz7u2eoCOPh7BZaef gUDrju/vqGT5A== Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4WTKTG0qZrz4x04; Wed, 24 Jul 2024 13:37:22 +1000 (AEST) Date: Wed, 24 Jul 2024 13:31:49 +1000 From: David Gibson To: Stefano Brivio Subject: Re: [PATCH v2] tcp: probe for SO_PEEK_OFF both in tcpv4 and tcp6 Message-ID: References: <20240722220937.3663437-1-sbrivio@redhat.com> <20240723222936.1c301d30@elisabeth> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="JYH8npRNivWt2YDw" Content-Disposition: inline In-Reply-To: Message-ID-Hash: OWT3SWUKXPPOHWIN4OO27AU5GJRCUP2S X-Message-ID-Hash: OWT3SWUKXPPOHWIN4OO27AU5GJRCUP2S 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, Jon Maloy 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: --JYH8npRNivWt2YDw Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jul 24, 2024 at 10:40:15AM +1000, David Gibson wrote: > On Tue, Jul 23, 2024 at 10:29:36PM +0200, Stefano Brivio wrote: > > On Tue, 23 Jul 2024 00:09:37 +0200 > > Stefano Brivio wrote: > >=20 > > > From: Jon Maloy > > >=20 > > > Based on an original patch by Jon Maloy: > > >=20 > >=20 > > ...so, with this, the probing issue is solved: on a 6.10 kernel, > > SO_PEEK_OFF is not used, unless I disable IPv6 (with --ipv4-only / -4). > >=20 > > However, if I disable it, for some reason, resorting to IPv4, at least > > together with the flow table (applying just this patch to HEAD), I get > > something that looks like one of the "old" TCP stalls. On the host: > >=20 > > $ ./passt -f -t 10000 -4 > >=20 > > and in the guest: > >=20 > > # ip link set dev eth0 up > > # dhclient eth0 > > # iperf3 -s -p 10000 > >=20 > > back to the host: > >=20 > > $ iperf3 -c 127.0.0.1 -p 10000 > > Connecting to host 127.0.0.1, port 10000 > > [ 5] local 127.0.0.1 port 39046 connected to 127.0.0.1 port 10000 > > [ ID] Interval Transfer Bitrate Retr Cwnd > > [ 5] 0.00-1.00 sec 11.2 MBytes 94.3 Mbits/sec 0 5.50 MByt= es =20 > > [ 5] 1.00-2.00 sec 0.00 Bytes 0.00 bits/sec 0 5.50 MBytes= =20 > > [ 5] 2.00-3.00 sec 0.00 Bytes 0.00 bits/sec 0 5.50 MBytes= =20 > >=20 > > ...the transfer never recovers. >=20 > Bother. I've reproduced and am debugging now. Found it. Looks like one of the cases where we need to set SO_PEEK_OFF was lost somewhere in the refactorings :(. > > I didn't really have time to debug this further. > >=20 > > At the moment I would be inclined to temporarily revert commit > > e63d281871ef ("tcp: leverage support of SO_PEEK_OFF socket option when > > available"), but it's not a good idea if this happens to be hiding some > > (unlikely?) issue with the flow table. > >=20 >=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 --JYH8npRNivWt2YDw Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEO+dNsU4E3yXUXRK2zQJF27ox2GcFAmagdaQACgkQzQJF27ox 2GcTQg/6A4kLMVhOH8ElzNBtv0DeG2s+nAoEtxa3Kus/XcMLp8cHtR2IbRI1aE0x 4K01MTwylLsq6/uFalBzfBGEfSI34mWn5OvHkxpvYcw9B4VurahoOKxdGsYHH7HX WQiZIJZhCM3I/z7K4tiqy70KLVakN/yy4t8mLdb2osgLeesxcy2MRE6e7MBUecai +j1zvB5UPrvQFtNFD5rtJmBPDHOF6K3D7vI+JLFRW02/QVELwuLoa0jo51H0B7XC 2YG7TrQbZbR6EjCY4BdM1GFgHJEMZNlEdniNt27mkJVN/4Nd4ceupdBLTQoQP69J ofTwr+dUziAPfHkGkj5Gof2gNqHwQsR91riwira/rzdhX9eRK/dZdVfoFEAFVzut 2sjaO3j+yxjmIrLDClPdhzGClir5nuPcqC49Zx8MnFZGpJ5wp2l/ecZEGpc4WS75 QN0wz1ahU8KaCS8GHL+AP/Nnd4l4V2HoHScLL2pL/z5sAJiUEsk3TYzvxTRwE3W6 FwGvxw7WQhMKRlH1H6x3F99zYCdhw3pPhfM3XbgJ4nSZrsigLo+53WzjhrhsAT8l cjTMfLWFSQW+qmTYcFwT3gXYvuIol79yWOZI2L3a88TriUf3jUAzBe0aunS5Fj2g mxbGdyQpDQV8VdpiSMmk3OpBTcanyPqyuWKCLNkE38R2KyZ3Nf0= =24tA -----END PGP SIGNATURE----- --JYH8npRNivWt2YDw--