Date: Thu, 10 Apr 2003 23:58:01 +0200 From: Mattias Pantzare <pantzer@ludd.luth.se> To: Terry Lambert <tlambert2@mindspring.com> Cc: David Gilbert <dgilbert@velocet.ca> Subject: Re: tcp_output starving -- is due to mbuf get delay? Message-ID: <3E95E8E9.3080102@ludd.luth.se> In-Reply-To: <3E95E446.73B7E510@mindspring.com> References: <20030410171640.C44793B2@porter.dc.luth.se> <3E95E446.73B7E510@mindspring.com>
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> >>What happens in that case for me is that I run out of CPU resources. Try >>running "top" in one window and "netstat 1" in another while bashing the >>net with ttcp. > > > This is incredibly bizarre. It's very hard to saturate the CPU > at only 1Gbit: in all cases, you are I/O bound, not CPU bound, > and not memory bandwidth bound > >>IMPORTANT NOTE: Several tests here has shown that this is VERY BADLY >>affected if You have too much LAN equipment (especially VLAN seems to be >>harmful) at the edges. My speed of 960 Mbit/sec fell to 165 just by adding >>10 feet of cable and two switches :-( > > > The products that Jeffrey Hsu and I and Alfred and Jon Mini > worked on at a previous company had no problems at all on a > 1Gbit/S saturating the link, even through a VLAN trunk through > Cisco and one other less intelligent switch (i.e. two switches > and a VLAN trunk). A key factor here is that the testst where on a link with a 20ms round-tip time, and using a singel TCP connection. So the switches where in addition to a few routers on a 10Gbit/s network.
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