Date: Sun, 19 Mar 2006 02:46:48 -0800 From: "Jin Guojun (VFFS)" <g_jin@lbl.gov> To: OxY <oxy@field.hu> Cc: freebsd-performance@freebsd.org Subject: Re: packet drop with intel gigabit / marwell gigabit Message-ID: <441D3698.10300@lbl.gov> In-Reply-To: <000401c64b33$7561d940$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>
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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? > i measured the network performance with 'iperf' util, started the > server on my box > and benchmarked with a client on the other gigabit machine. > it showed 0% packet drop, when apache was not running and 4-7%, when > running.. > then i checked how it behave when i shut down apache and init a local > file copy from one > (not system!) disk to other (not system disk either). packet drop was > 5-10%, due to the higher load. > so i think interrupts or just the load takes the network performance, > but i have no clue how to fix it. > is it possible that the 2000+ xp amd is just weak to serve such a > traffic? (em0 traffic's maximum is 18-23MB/s) > i think it might be around 30MB/s without packet drop. 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? > I did FTP measurement, because what i want is to copy files with high > speed from the > other gigabit machine. However FTP needs resources (CPU, I/O, etc), > but iperf not! > iperf shows 20% CPU utilization when apache not running and when > there's no packet drop. > > ps: Now apache says: 14 requests currently being processed > traffic is 1MB/s on fxp0, and em0 benchmark with iperf says (64k udp > window size): > > [ 3] 0.0-10.0 sec 235 MBytes 197 Mbits/sec > [ 3] Sent 167375 datagrams > [ 3] Server Report: > [ 3] 0.0-10.0 sec 229 MBytes 192 Mbits/sec 0.066 ms > 4115/167375 (2.5%) > > the other gigabit machine is OK, because i have 0% packet drop, when > my machine is totally idle.
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