Date: Mon, 26 Jun 2017 16:13:33 +0300 From: "Andrey V. Elsukov" <bu7cher@yandex.ru> To: Ryan Stone <rysto32@gmail.com>, Ben RUBSON <ben.rubson@gmail.com> Cc: FreeBSD Net <freebsd-net@freebsd.org>, "freebsd-scsi@freebsd.org" <freebsd-scsi@freebsd.org> Subject: Re: mbuf_jumbo_9k & iSCSI failing Message-ID: <64abec26-e310-d66d-93ae-3536914ddd84@yandex.ru> In-Reply-To: <CAFMmRNwbEwn=TmTAd56rViDV5nDXq_hPmTp-cDwmVqu1XYm=fA@mail.gmail.com> References: <486A6DA0-54C8-40DF-8437-F6E382DA01A8@gmail.com> <6a31ef00-5f7a-d36e-d5e6-0414e8b813c7@selasky.org> <DB3PR05MB089A5789A0A619FA8B7CA36C36C0@DB3PR05MB089.eurprd05.prod.outlook.com> <613AFD8E-72B2-4E3F-9C70-1D1E43109B8A@gmail.com> <2c9a9c2652a74d8eb4b34f5a32c7ad5c@AM5PR0502MB2916.eurprd05.prod.outlook.com> <DB3PR05MB089011A41EF87A40C7AC741C36E0@DB3PR05MB089.eurprd05.prod.outlook.com> <F19B51C7-7DDD-4FAB-9091-0B7C8A7CE649@gmail.com> <52A2608C-A57E-4E75-A952-F4776BA23CA4@gmail.com> <9B507AA6-40FE-4B8D-853F-2A9422A2DF67@gmail.com> <CAFMmRNzo=xB8XF6SFD%2BwksmBYjRZ_peYjiPBCXNVyqP%2BdxnujQ@mail.gmail.com> <CAFMmRNwbEwn=TmTAd56rViDV5nDXq_hPmTp-cDwmVqu1XYm=fA@mail.gmail.com>
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This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --smqF3QFS4WoFbpvK6WMrFmhjvPMtBWeiE Content-Type: multipart/mixed; boundary="LXCCDuFkvV5DOvwWRd8qkkXQ6ssJnmhDg"; protected-headers="v1" From: "Andrey V. Elsukov" <bu7cher@yandex.ru> To: Ryan Stone <rysto32@gmail.com>, Ben RUBSON <ben.rubson@gmail.com> Cc: FreeBSD Net <freebsd-net@freebsd.org>, "freebsd-scsi@freebsd.org" <freebsd-scsi@freebsd.org> Message-ID: <64abec26-e310-d66d-93ae-3536914ddd84@yandex.ru> Subject: Re: mbuf_jumbo_9k & iSCSI failing References: <486A6DA0-54C8-40DF-8437-F6E382DA01A8@gmail.com> <6a31ef00-5f7a-d36e-d5e6-0414e8b813c7@selasky.org> <DB3PR05MB089A5789A0A619FA8B7CA36C36C0@DB3PR05MB089.eurprd05.prod.outlook.com> <613AFD8E-72B2-4E3F-9C70-1D1E43109B8A@gmail.com> <2c9a9c2652a74d8eb4b34f5a32c7ad5c@AM5PR0502MB2916.eurprd05.prod.outlook.com> <DB3PR05MB089011A41EF87A40C7AC741C36E0@DB3PR05MB089.eurprd05.prod.outlook.com> <F19B51C7-7DDD-4FAB-9091-0B7C8A7CE649@gmail.com> <52A2608C-A57E-4E75-A952-F4776BA23CA4@gmail.com> <9B507AA6-40FE-4B8D-853F-2A9422A2DF67@gmail.com> <CAFMmRNzo=xB8XF6SFD+wksmBYjRZ_peYjiPBCXNVyqP+dxnujQ@mail.gmail.com> <CAFMmRNwbEwn=TmTAd56rViDV5nDXq_hPmTp-cDwmVqu1XYm=fA@mail.gmail.com> In-Reply-To: <CAFMmRNwbEwn=TmTAd56rViDV5nDXq_hPmTp-cDwmVqu1XYm=fA@mail.gmail.com> --LXCCDuFkvV5DOvwWRd8qkkXQ6ssJnmhDg Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 25.06.2017 18:32, Ryan Stone wrote: > Having looking at the original email more closely, I see that you showe= d an > mlxen interface with a 9020 MTU. Seeing allocation failures of 9k mbuf= > clusters increase while you are far below the zone's limit means that > you're definitely running into the bug I'm describing, and this bug cou= ld > plausibly cause the iSCSI errors that you describe. >=20 > The issue is that the newer version of the driver tries to allocate a > single buffer to accommodate an MTU-sized packet. Over time, however, > memory will become fragmented and eventually it can become impossible t= o > allocate a 9k physically contiguous buffer. When this happens the driv= er > is unable to allocate buffers to receive packets and is forced to drop > them. Presumably, if iSCSI suffers too many packet drops it will termi= nate > the connection. The older version of the driver limited itself to > page-sized buffers, so it was immune to issues with memory fragmentatio= n. I think it is not mlxen specific problem, we have the same symptoms with ixgbe(4) driver too. To avoid the problem we have patches that are disable using of 9k mbufs, and instead only use 4k mbufs. --=20 WBR, Andrey V. Elsukov --LXCCDuFkvV5DOvwWRd8qkkXQ6ssJnmhDg-- --smqF3QFS4WoFbpvK6WMrFmhjvPMtBWeiE Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEzBAEBCAAdFiEE5lkeG0HaFRbwybwAAcXqBBDIoXoFAllRCH0ACgkQAcXqBBDI oXobwAf+Lxnto9w+KaTuAIkktZnoN42kjUNtY1bMNFn5amhEgFNlUeQxqFymZdvQ h7f2cAiNJ3SLVxiw/cxbeOK4r2Bk53JwNBEwI/VtyNCDLyikJ7Ov8yVOAgG4RydA llp+ZXsko19zxdlR5aBW140egiRCXTMvbNZ4IoqE3GiHwS6TDEFglbbEbUJK0r9l A9zlW+0EAxo3UELSQhfymIALfXHCPLzM0AYf/VvWdvNIio3Y1ZMeZK6Rkofgefux yddJnL54pVWKz1LvfuSEtE+wW9Tm/nF2MeRrdLKsiSWJGuUwTKlMq4porJ3K0Viq V6MHyi2U7818TQcDBbOkwrztEL9l3w== =S8WI -----END PGP SIGNATURE----- --smqF3QFS4WoFbpvK6WMrFmhjvPMtBWeiE--
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