Date: Fri, 4 Jul 2014 12:25:35 +0200 From: Luigi Rizzo <rizzo@iet.unipi.it> To: Slawa Olhovchenkov <slw@zxy.spb.ru> Cc: Kevin Oberman <rkoberman@gmail.com>, Sreenivasa Honnur <shonnur@chelsio.com>, FreeBSD Current <freebsd-current@freebsd.org>, Nikolay Denev <ndenev@gmail.com> Subject: Re: FreeBSD iscsi target Message-ID: <CA%2BhQ2%2BgcWOiXvoq4a6UY8UWOqOZT%2BwfaBS7mFNs9LoKKEEDfJw@mail.gmail.com> In-Reply-To: <20140704101626.GB58753@zxy.spb.ru> References: <20140701091252.GB3443@brick> <20140701231305.GA37246@zxy.spb.ru> <CAN6yY1t2qDzfeO37p2s_3=vzEVv5C813M0ttqjnM4tJGkkBhyA@mail.gmail.com> <20140702112609.GA85758@zxy.spb.ru> <CAN6yY1uzfjoDfEdti91Ogy11LzT3-5JvLREBdW6ynEOgm0uUPA@mail.gmail.com> <20140702203603.GO5102@zxy.spb.ru> <CAN6yY1von-Z586V=8qs3%2BOfV3oXes380s2GD-149EYWLxws-qA@mail.gmail.com> <CA%2BP_MZE013dv22Sb-rk7ZoiYbCTodmth0d-XpdM6mrpw3WxQmg@mail.gmail.com> <20140703091321.GP5102@zxy.spb.ru> <CAN6yY1uk8ooCjWzH=Zxyjm8UhgEm3dVPfc7ZOV1LR3%2B3DfnyHA@mail.gmail.com> <20140704101626.GB58753@zxy.spb.ru>
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On Fri, Jul 4, 2014 at 12:16 PM, Slawa Olhovchenkov <slw@zxy.spb.ru> wrote: > On Thu, Jul 03, 2014 at 08:39:42PM -0700, Kevin Oberman wrote: > > > > > > > In real world "Reality is quite different than it actually is". > > > > > > > http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-6500-series-switches/white_paper_c11-696669.html > > > > > > See "Packet Path Theory of Operation. Ingress Mode". > > > > > > > > Yep. It is really crappy LAGG (fixed three-tupple hash... yuck!) and is > > really nothing but 4 10G Ethernet ports using a 40G PHY in yhe 4x10G > form. > > > > Note that they don't make any claim of 802.3ba compliance. It only states > > that "40 Gigabit Ethernet is now part of the IEEE 802.3ba standard." So > it > > is, but this device almost certainly predates the completion of the > > standard to get a product for which there was great demand. It's a data > > center product and for typical cases of large numbers of small flow, it > > should do the trick. Probably does not interoperate with true 80-2.3ba > > hardware, either. > > > > My boss at the time I retired last November was on the committee that > wrote > > 802.3ba. He would be a good authority on whether the standard has any > vague > > wording that would allow this, but he retired 5 month after I did and I > > have no contact information for him. But I'm pretty sure that there is no > > way that this is legitimate 40G Ethernet. > > 802.3ba describe only end point of ethernet. > ASIC, internal details of implemetations NICs, switches, fabrics -- > out of standart scope. > Bottleneck can be in any point of packet flow. > In first pappers of netmap test demonstarated NIC can't do saturation > of 10G in one stream 64 bytes packet -- need use multiple rings for > transmit. > that was actually just a configuration issue which since then has been resolved. The 82599 can do 14.88 Mpps on a single ring (and is the only 10G nic i have encountered who can do so). Besides, performance with short packets has nothing to do with the case you were discussing, namely throughput for a single large flow. > I think need use general rule: one flow transfer can hit performance > limitation. > This is neither a useful nor it is restricted to a single flow. Everything "can" underperform depending on the hw/sw configuration, but not necessarily has to. cheers luigi
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