Date: Mon, 20 Mar 2006 11:22:17 +0100 From: "OxY" <oxy@field.hu> To: "Jin Guojun [VFFS]" <g_jin@lbl.gov> Cc: freebsd-performance@freebsd.org Subject: Re: packet drop with intel gigabit / marwell gigabit Message-ID: <000601c64c08$2a7b4990$0201a8c0@oxy> References: <000a01c64a81$45eb6850$0201a8c0@oxy> <441BF838.1080600@mac.com><000601c64a87$51d7dee0$0201a8c0@oxy> <441BFF26.90807@mac.com> <000e01c64a8f$1b2bec80$0201a8c0@oxy> <441CAA8D.3020308@lbl.gov> <000401c64b33$7561d940$0201a8c0@oxy> <441D3698.10300@lbl.gov> <000601c64b44$db8dcb00$0201a8c0@oxy> <441E1BF1.6050205@lbl.gov>
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----- Original Message ----- From: "Jin Guojun [VFFS]" <g_jin@lbl.gov> To: "OxY" <oxy@field.hu> Cc: <freebsd-performance@freebsd.org> Sent: Monday, March 20, 2006 4:05 AM Subject: Re: packet drop with intel gigabit / marwell gigabit > OxY wrote: > >> >> ----- Original Message ----- From: "Jin Guojun (VFFS)" <g_jin@lbl.gov> >> To: "OxY" <oxy@field.hu> >> Cc: "Chuck Swiger" <cswiger@mac.com>; <freebsd-performance@freebsd.org> >> Sent: Sunday, March 19, 2006 11:46 AM >> Subject: Re: packet drop with intel gigabit / marwell gigabit >> >> >>> OxY wrote: >>> >>>> CPU utilization is 0% if apache is not running and 10-20%, when running >>>> and >>>> serving 30-40 concurrent downloads (traffic is 3-4MB/s on fxp0 >>>> interface) >>> >>> >>> Is the number 3-4MB/s for per stream or the total for all 30-40 >>> streams? >>> Are these downloads sent to a disk? >> >> >> it's a total, 30-40 streams get the files from two sata disks in raid1 >> >>> .... >>> First let's clear the notation -- Is 30MB/s (MBytes/s) = 240Mb/s >>> (Mbit/s) or MB/s means Mbits/s >>> If MB/s is MBytes/s and you also write this amount data to a disk, plus >>> other traffic on fxp0 to disk too, >>> then your problem may be bonded by memory bandwidth because CPU >>> utilization is low: >>> (240 + 24~32) x 2 is about 535 Mbit/s (some chipset/motherboard has >>> low memory BW for AMD) >>> If this is true, then this no thing you can tune. What does the chipset >>> (Motherboard) this machine have? >> >> >> 30MB/s is Megabytes/sec, currently i have 18-20MB/s peak and 15MB/s avg. >> it's not 535Mbit/s, because i only download it to my machine, no upload. >> disks are different from apache disks, these disks have own controller in >> one pci slot. >> the packet drop is 5-7% at 200Mbit iperf test, 100Mbit drop is around >> zero. >> i have <ASUS A7V8X> on motherboard which has VIA KT400 northbridge >> http://uk.asus.com/products4.aspx?modelmenu=2&model=226&l1=3&l2=13&l3=62 > > Yes, this is one of problem chipset. I bought one about 3 years ago. > After one day testing, I returned it for changing a A7V600 (VIA KT600 > chipset), > which is 30% more memory bandwidth than KT400. A7V600 can only receive max > 604 Mb/s TCP, so You can imagine what the KT400 can do :-) > I do not have a record (because it is too bad), but taking minimum 25% > off, > it probably about 420-430 Mb/s (50MB/s). Now you can do the math when the > machine also writing data to a disk (assume disk a fast enough). I would > expect > 2/3 of 430 Mb/s, which is about 280~290 Mb/s (35 MB/s). > If you experiment these numbers, you are at there. No improvement you can > make > further. i have doubts, because when i have 3-4MB/s traffic on fxp0 then em0 peak is 18MB/s, but when fxp0 is almost idle, have 500kB/s traffic, then em0 can only do 20MB/s.. > AMD is good. As I mentioned earlier, it is motherboard shipset make's > problem. > I like AMD CPU, and I amd writing from A7V600 with AMD XP 2100+ :-) > > The ABIT motherboard has an Intel 845 chipset, which has very good memory > bandwidth. > You should be able to saturate your GigE interface on this motherboard. > If you have problem to obtain the performance, we can tune it . > Good luck! okay, i check with intel soon :) > > -Jin >
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