Date: Sat, 4 May 2013 14:19:51 -0700 From: Richard Sharpe <realrichardsharpe@gmail.com> To: Jack Vogel <jfvogel@gmail.com> Cc: FreeBSD Net <freebsd-net@freebsd.org>, Adrian Chadd <adrian@freebsd.org> Subject: Re: Is there any way to limit the amount of data in an mbuf chain submitted to a driver? Message-ID: <CACyXjPyr40D-4G4QDHbAgiMY-9o5YYvOtuDEUCjvQDCyYaPZMw@mail.gmail.com> In-Reply-To: <CAFOYbckUzavh5W7BoChg7Dg7cGPK7JLJ5O3Mc8syAYa9LQKcxg@mail.gmail.com> References: <CACyXjPwC5LRb7DT82n6PMbawceER3_nHko9c9tvrdQqceLiPww@mail.gmail.com> <CAJ-Vmon_5eyXMP5UOsVVBP8UgKQLw5HLMO1NgswoGb-zF=2wtg@mail.gmail.com> <CACyXjPzu3fXpo0i5YcdVBFye%2BRFTPUye=fgZ%2BycTkkiEmcRh%2BQ@mail.gmail.com> <CAFOYbcmZMW=-7Mwz9mwJLeM3Ju%2BF8_AsXFAPqCa8%2BuuRWq3xsg@mail.gmail.com> <CACyXjPy=ErKS_A3Nmwa8PnMc_D=2LByd4VJPFdTj9sqgSaCTfw@mail.gmail.com> <CAFOYbckUzavh5W7BoChg7Dg7cGPK7JLJ5O3Mc8syAYa9LQKcxg@mail.gmail.com>
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On Sat, May 4, 2013 at 2:18 PM, Jack Vogel <jfvogel@gmail.com> wrote: > Ahh, Twinville, new hardware :) The version at the tip is 2.5.8 and I am > working on version 2.5.12 internally that I hope to commit next week... > so your version is "a bit old" :) I would do some testing on newer code. I would love to. Where is the repo. > Jack > > > > On Sat, May 4, 2013 at 1:54 PM, Richard Sharpe <realrichardsharpe@gmail.c= om> > wrote: >> >> On Sat, May 4, 2013 at 1:41 PM, Jack Vogel <jfvogel@gmail.com> wrote: >> > If you don't use TSO you will hurt your TX performance significantly >> > from >> > the tests that I've run. What exactly is the device you are using, I >> > don't >> > have the source in front of me now, but I'm almost sure that the limit >> > is >> > not 64K but 256K, or are you using some ancient version of the driver? >> >> ix0 pnpinfo vendor=3D0x8086 device=3D0x1528 subvendor=3D0x80= 86 >> subdevice=3D0x0001 class=3D0x020000 at slot=3D0 function=3D0 >> ix1 pnpinfo vendor=3D0x8086 device=3D0x1528 subvendor=3D0x80= 86 >> subdevice=3D0x0001 class=3D0x020000 at slot=3D0 function=3D1 >> >> The version calls itself ixgbe-2.4.4 ... >> >> Hmmm, copyright is 2001-2010 ... so perhaps a bit old. >> >> > Jack >> > >> > >> > >> > On Sat, May 4, 2013 at 1:30 PM, Richard Sharpe >> > <realrichardsharpe@gmail.com> >> > wrote: >> >> >> >> On Sat, May 4, 2013 at 10:39 AM, Adrian Chadd <adrian@freebsd.org> >> >> wrote: >> >> > 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 larg= er >> >> >> than that. >> >> >> >> >> >> The SO_SNDBUF for that socket is set to 131972. Mostly there is le= ss >> >> >> 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 contin= ue >> >> >> to use SO_SNDBUF sizes larger than 65536 is to fragment large mbuf >> >> >> chains in the driver? >> >> > >> >> > Hm, is this is a problem without TSO? >> >> >> >> We are using the card without TSO, so I am thinking of changing that >> >> limit to 131072 and retesting. >> >> >> >> I am currently testing with SO_SNDBUF=3D32768 and have not hit the >> >> problem. >> >> >> >> > Is the problem that the NIC can't handle a frame that big, or a >> >> > buffer >> >> > that big? >> >> > Ie - if you handed the hardware two descriptors of 64k each, for th= e >> >> > same IP datagram, will it complain? >> >> >> >> I can't find any documentation, but it seems that with TSO it cannot >> >> handle a frame that big. Actually, since we are not using TSO, there >> >> really should not be a problem with larger frames. >> >> >> >> > Or do you need to break it up into two separate IP datagrams, facin= g >> >> > the driver, with a maximum size of 64k each? >> >> >> >> Not sure, but it looks like we need to do that. >> >> >> >> >> >> -- >> >> 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= " >> > >> > >> >> >> >> -- >> Regards, >> Richard Sharpe >> (=A6=F3=A5H=B8=D1=BC~=A1H=B0=DF=A6=B3=A7=F9=B1d=A1C--=B1=E4=BE=DE) > > --=20 Regards, Richard Sharpe (=A6=F3=A5H=B8=D1=BC~=A1H=B0=DF=A6=B3=A7=F9=B1d=A1C--=B1=E4=BE=DE)
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