Date: Thu, 21 Mar 2002 04:25:28 -0600 (CST) From: Haryadi Gunawi <haryadi@cs.wisc.edu> To: net@freebsd.org Subject: bug in xl_intr (an 'xl' interrupt function)? Message-ID: <Pine.LNX.4.21.0203210405520.5872-100000@tux12.cs.wisc.edu> In-Reply-To: <Pine.LNX.4.21.0203210032380.6631-100000@tux19.cs.wisc.edu>
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Hi, I have FreeBSD 4.4, and I wrote simple TCP and UDP progras bacically the client sends some bytes and the server echo the messages. I use Ethernet which MTU is around 1400++ (I forget exactly), and the NIC is "3Com Fast EtherLink XC PCI3Com Fast EtherLink XC PCI". Using sample based profiling system I can obtain the timing distribution for "xl_intr" function (in src/sys/pci/if_xl.c): Bytes %-tcp %-udp 0200 0.01 0.01 1000 0.02 0.01 1200 0.01 0.01 1400 0.03 0.01 1450 18.12 0.01 <---- 1500 21.78 0.01 1600 19.07 0.01 3000 16.06 0.01 What the table means is that (for the 1st row), If I ran the program using TCP, when sending and receiving 200 bytes messages, the xl_intr routine only spend 0.01 % of the Overhead Processing Time (not include the transmission time). --> Now the weird result (for TCP) is that after it hits the MTU (1400+), the xl_intr suddenly jumps SPENDING MORE THAN 15% of the overhead processing time. I don't know whether this is the correct result or not. But it seems a bug to me. I don't think a device protocol should spend that much time. The long time spent is not in other functions called from xl_intr, but in the body of the xl_intr itself. Can anyone help me find out what's going on here? or if this is too details, can someone please tell me where I can find the 'xl' functions documentation (very detail one, the structure, implementation, etc ...). Thank you very much for your time appreciate it Haryadi To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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