Date: Sat, 4 May 2013 10:39:43 -0700 From: Adrian Chadd <adrian@freebsd.org> To: Richard Sharpe <realrichardsharpe@gmail.com> Cc: freebsd-net@freebsd.org Subject: Re: Is there any way to limit the amount of data in an mbuf chain submitted to a driver? Message-ID: <CAJ-VmokFD0dH=ik=X5Jm8DqZdfXBWba1T%2BGPmCahaCmyFoqUOQ@mail.gmail.com> In-Reply-To: <CACyXjPwC5LRb7DT82n6PMbawceER3_nHko9c9tvrdQqceLiPww@mail.gmail.com> References: <CACyXjPwC5LRb7DT82n6PMbawceER3_nHko9c9tvrdQqceLiPww@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
.. and please file a PR. I'm sure Jack will love this kind of feedback. :) Thanks for doing this debugging! I'm glad to see others getting dirty in the network stack. Adrian On 4 May 2013 06:52, Richard Sharpe <realrichardsharpe@gmail.com> wrote: > Hi folks, > > I understand better why I am seeing EINVAL intermittently when sending > data from Samba via SMB2. > > The ixgbe driver, for TSO reasons, limits the amount of data that can > be DMA'd to 65535 bytes. It returns EINVAL for any mbuf chain larger > than that. > > The SO_SNDBUF for that socket is set to 131972. Mostly there is less > than 64kiB of space available, so that is all TCP etc can put into the > socket in one chain of mbufs. However, every now and then there is > more than 65535 bytes available in the socket buffers, and we have an > SMB packet that is larger than 65535 bytes, and we get hit. > > To confirm this I am going to set SO_SNDBUF back to the default of > 65536 and test again. My repros are very reliable. > > However, I wondered if my only way around this if I want to continue > to use SO_SNDBUF sizes larger than 65536 is to fragment large mbuf > chains in the driver? > > -- > Regards, > Richard Sharpe > (=A6=F3=A5H=B8=D1=BC~=A1H=B0=DF=A6=B3=A7=F9=B1d=A1C--=B1=E4=BE=DE) > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAJ-VmokFD0dH=ik=X5Jm8DqZdfXBWba1T%2BGPmCahaCmyFoqUOQ>