I'm seeing really bizarre behavior when reading from /proc/net/tcp. On a completely unloaded system (4 CPUs, no application processes running), it can take multiple seconds just to cat this file. The /proc/net/tcp file only has 21 lines in it, so it isn't like there are just tons of socket connections. Here's an example: [root@hpq11 root]# time cat /proc/net/tcp > /dev/null real 0m3.253s user 0m0.000s sys 0m0.000s However, if the system is really loaded (I'm running make -j 8 bzImage), it speeds up: [root@hpq11 root]# time cat /proc/net/tcp > /dev/null real 0m0.487s user 0m0.000s sys 0m0.000s I searched around on google and could only find the following discussion: http://www.ussg.iu.edu/hypermail/linux/kernel/0110.2/0475.html However, it is from 2001 so I'm not really sure how relevant it is. The machine in question has 2 GB of RAM. dmesg displays the following output: [root@hpq11 etc]# dmesg | grep Hash TCP: Hash tables configured (established 524288 bind 65536) The above mentioned thread seems to say that the TCP Connection Hash Table Size is too big, and that is why /proc/net/tcp takes so long. However, it offers no information on how to correct the problem, and I can't seem to find any documentation that tells me what tunable I need to modify to make this problem go away (is there a way to reduce the hash table size?). An identical machine with the same memory size and same kernel (and same dmesg output) does not have this problem. Both machines are running Redhat 3 Update 3. If this problem has already been discussed ad nauseum, any help or quick pointer would be very much appreciated. Regards, Chad - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
