Date: Thu, 4 Aug 2016 17:33:19 +0200 From: Ben RUBSON <ben.rubson@gmail.com> To: freebsd-net@freebsd.org Subject: Re: Unstable local network throughput Message-ID: <E5BE8DAC-AB6A-491E-A901-4E513367278B@gmail.com> In-Reply-To: <0b14bf39-ed71-b9fb-1998-bd9676466df6@selasky.org> References: <3C0D892F-2BE8-4650-B9FC-93C8EE0443E1@gmail.com> <bed13ae3-0b8f-b1af-7418-7bf1b9fc74bc@selasky.org> <3B164B7B-CBFB-4518-B57D-A96EABB71647@gmail.com> <5D6DF8EA-D9AA-4617-8561-2D7E22A738C3@gmail.com> <06E414D5-9CDA-46D1-A26F-0B07E76FDB34@gmail.com> <0b14bf39-ed71-b9fb-1998-bd9676466df6@selasky.org>
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> On 04 Aug 2016, at 17:33, Hans Petter Selasky <hps@selasky.org> wrote: > > On 08/04/16 17:24, Ben RUBSON wrote: >> >>> On 04 Aug 2016, at 11:40, Ben RUBSON <ben.rubson@gmail.com> wrote: >>> >>>> On 02 Aug 2016, at 22:11, Ben RUBSON <ben.rubson@gmail.com> wrote: >>>> >>>>> On 02 Aug 2016, at 21:35, Hans Petter Selasky <hps@selasky.org> wrote: >>>>> >>>>> The CX-3 driver doesn't bind the worker threads to specific CPU cores by default, so if your CPU has more than one so-called numa, you'll end up that the bottle-neck is the high-speed link between the CPU cores and not the card. A quick and dirty workaround is to "cpuset" iperf and the interrupt and taskqueue threads to specific CPU cores. >>>> >>>> My CPUs : 2x E5-2620v3 with DDR4@1866. >>> >>> OK, so I cpuset all Mellanox interrupts to one NUMA, as well as the iPerf processes, and I'm able to reach max bandwidth. >>> Choosing the wrong NUMA (or both, or one for interrupts, the other one for iPerf, etc...) totally kills throughput. >>> >>> However, full-duplex throughput is still limited, I can't manage to reach 2x40Gb/s, throttle is at about 45Gb/s. >>> I tried many different cpuset layouts, but I never went above 45Gb/s. >>> (Linux allowed me to reach 2x40Gb/s so hardware is not a bottleneck) >>> >>>>> Are you using "options RSS" and "options PCBGROUP" in your kernel config? >>> >>> I will then give RSS a try. >> >> Without RSS : >> A ---> B : 40Gbps (unidirectional) >> A <--> B : 45Gbps (bidirectional) >> >> With RSS : >> A ---> B : 28Gbps (unidirectional) >> A <--> B : 28Gbps (bidirectional) >> >> Sounds like RSS does not help :/ >> >> Why, without RSS, do I have difficulties to reach 2x40Gbps (full-duplex) ? >> > > Hi, > > Possibly because the packets are arriving at the wrong CPU compared to what RSS expects. Then RSS will invoke a taskqueue to process the packets on the correct CPU, if I'm not mistaken. But even without RSS, I should be able to go up to 2x40Gbps, don't you think so ? Nobody already did this ?
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