Messages in this thread | | | Date | Tue, 30 Jan 2001 10:32:08 -0700 | From | "Jeff V. Merkey" <> | Subject | Re: [ANNOUNCE] Dolphin PCI-SCI RPM Drivers 1.1-4 released |
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On Tue, Jan 30, 2001 at 10:19:58AM -0700, Jeff V. Merkey wrote: > On Mon, Jan 29, 2001 at 09:41:21PM -0700, Todd wrote:
Todd,
I just got back some more numbers from Dolphin. The newer D330 LC3 chipsets are running at 667 MB/S Link speed, and on a Serverworks HE system, we are seeing 240 MB/S throughput via the newer PCI-SCI adapters. I have some D330 adapters on the way here, and will repost newer numbers after the Alpha changes are rolled in and I repost the drivers again next week sometime.
On 32 bit PCI, the average we are seeing going userpace -> userspace is 120-140 MB/S ranges in those systems that have a PCI bus with bridge chipsets that can support these data rates.
That's 2 x G-Enet.
:-)
Jeff
> > Todd, > > I ran the tests on a box that has a limit of 70MB/S PCI throughput. > There are GaAs (Gallium Arsenide) implementations of SCI that run > well into the Gigabyte Ranges, and I've seen some of this hardware. > The NUMA-Q chipsets in Sequents cluster boxes are actually SCI. > Sun Microsystems uses SCI as their clustering interconnect for their > Sparc servers. The adapters these drivers I posted support are a bi-CMOS > implementation of the SCI LC3 chipsets, and even though they are > bi-CMOS, the Link speed on the back end is still 500 MB/S -- > very respectable. > > The PCI-SCI cards these drivers support in PCI systems have been clocked up > to 140 MB/S+ on those systems that have enough bandwidth to actually > push this much data. These boards can pump up to 500MB/S over the > SCI fabric, however, current PCI technology doesn't allow you to > push this much data. I also tested on the D320 chipsets, the newer > D330 chipsets on the PSB66 cards support the 66Mhz bus and have been > measured up to the Max PCI speeds. > > The PCI-SCI adapters run circles around G-Enet on systems that can > really pump this much data through the PCI bus. Also, the numbers I > posted are doing push/pull DMA transfers between user_space -> user_space > in another system with **NO COPYING**. Ethernet and LAN networking always > copies data into userspace -- SCI has the ability to dump it directly > into user space pages without copying. That's what is cool about SCI, > you can pump this data around with almost no processor utilization -- > important on a cluster if you are doing computational stuff -- you need > every cycle you can squeeze, and don't want to waste them copying > data all over the place. Sure, G-Enet can pump 124 MB/S, but the > processor utilitzation will be high, and there will be lots of > copying going on in the system. What numbers does G-Enet provide > doing userspace -> userspace transfers, and at what processor > overhead? These are the types of things that are the metrics for > a good comparison. Also, G-Enet has bandwidth limitations, the > SCI standard does not, it's only limited by the laws of Physics > (which are being reached in the Dolphin Labs in Norway). > > The GaAs SCI technology I have seen has hop latencies in the SCI > switches @ 16 nano-seconds to route a packet, with xfer rates into > the Gigabytes per second -- very fast and low latency. > > These cards will use whatever PCI bandwidth is present in the host > system, up to 500 MB/S. As the PCI bus gets better, nice to know > SCI is something that will keep it's value, since 500 MB/S gives us > a lot of room to grow into. > > I could ask Dolphin for a GaAs version of the LC3 card (one board would > cost the equivalent to the income of a small third world nation), and > rerun the tests on a Sparc system or Sequent system, and watch G-Enet > system suck wind in comparison. > > :-) > > I posted the **ACCURATE** numbers from my test, but I did clarify that I > was using a system with a limp PCI bus. > > Jeff > > > > folx, > > > > i must be missing something here. i'm not aware of a PCI bus that only > > supports 70 MBps but i am probably ignorant. this is why i was confused > > by jeff's performance numbers. 33MHz 32-bit PCI busses should do around > > 120MB/s (just do the math 33*32/8 allowing for some overhead of PCI bus > > negotiation), much greater than the numbers jeff is reporting. 66 MHz > > 64bit busses should do on the order of 500MB/s. > > > > the performance numbers that jeff is reporting are not very impressive > > even for the slowest PCI bus. we're seeing 993 Mbps (124MB/s) using the > > alteon acenic gig-e cards on 32-bit cards on a 66MHz bus. i would expect > > to get somewhat slower on a 33MHz bus but not catastrophically so > > (certainly nothing as slow as 60MB/s or 480Mb/s). > > > > what am i misunderstanding here? > > > > todd > > > > On Mon, 29 Jan 2001, Jeff V. Merkey wrote: > > > > > Date: Mon, 29 Jan 2001 16:49:53 -0700 > > > From: Jeff V. Merkey <jmerkey@vger.timpanogas.org> > > > To: linux-kernel@vger.kernel.org > > > Cc: jmerkey@timpanogas.org > > > Subject: Re: [ANNOUNCE] Dolphin PCI-SCI RPM Drivers 1.1-4 released > > > > > > > > > Relative to some performance questions folks have asked, the SCI > > > adapters are limited by PCI bus speeds. If your system supports > > > 64-bit PCI you get much higher numbers. If you have a system > > > that supports 100+ Megabyte/second PCI throughput, the SCI > > > adapters will exploit it. > > > > > > This test was performed in on a 32-bit PCI system with a PCI bus > > > architecture that's limited to 70 MB/S. > > > > > > Jeff > > > > > > - > > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > > the body of a message to majordomo@vger.kernel.org > > > Please read the FAQ at http://www.tux.org/lkml/ > > > > > > > ========================================================= > > Todd Underwood, todd@unm.edu > > > > criticaltv.com > > news, analysis and criticism. about tv. > > and other stuff. > > > > ========================================================= > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > Please read the FAQ at http://www.tux.org/lkml/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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