Date: Tue, 27 Jun 2017 01:13:18 -0400 From: Zaphod Beeblebrox <zbeeble@gmail.com> To: Ben RUBSON <ben.rubson@gmail.com> Cc: Ryan Stone <rysto32@gmail.com>, FreeBSD Net <freebsd-net@freebsd.org>, "freebsd-scsi@freebsd.org" <freebsd-scsi@freebsd.org> Subject: Re: mbuf_jumbo_9k & iSCSI failing Message-ID: <CACpH0Me=sBhF=Ye=VnBO_fY=zpT203zCWqLhEZMkQ70kQdO_2g@mail.gmail.com> In-Reply-To: <14CB3F50-0426-48BD-838C-943B6D15FEB9@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> <14CB3F50-0426-48BD-838C-943B6D15FEB9@gmail.com>
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Don't forget that, generally, as I understand it, the network stack suffers from the same problem for 9k buffers. On Sun, Jun 25, 2017 at 12:56 PM, Ben RUBSON <ben.rubson@gmail.com> wrote: > > On 25 Jun 2017, at 17:32, Ryan Stone <rysto32@gmail.com> wrote: > > > > Having looking at the original email more closely, I see that you showed > 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 could > plausibly cause the iSCSI errors that you describe. > > > > 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 to > allocate a 9k physically contiguous buffer. When this happens the driver > is unable to allocate buffers to receive packets and is forced to drop > them. Presumably, if iSCSI suffers too many packet drops it will terminate > the connection. The older version of the driver limited itself to > page-sized buffers, so it was immune to issues with memory fragmentation. > > Thank you for your explanation Ryan. > You say "over time", and you're right, I have to wait several days (here > 88) before the problem occurs. > Strange however that in 2500MB free memory system is unable to find 9k > physically contiguous. But we never know :) > > Let's then wait for your patch ! > (and reboot for now) > > Many thx ! > > Ben > _______________________________________________ > freebsd-net@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" >
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