Squid is slower on FreeBSD 3.x?

Recently, we have upgraded three of our proxy servers from squid 2.2 on
FreeBSD 2.2CAM to squid 2.3 on FreeBSD 3.4. However, we notice that the
performance is poorer than before. We have tried to monitor the
performance by using mrtg. We notice the following:

All of them have around 2000req/min during 11am to 4pm.
                                Median Service Time LRU
                                (cache miss)
a. squid 2.2 on FreeBSD 2.2CAM < 340ms 6-7 days
(cachedir mounted as async, 4G)

b. squid 2.2 on FreeBSD 3.4 < 1s < 2 days
(cachedir mounted as async, 9G)

c. squid 2.3 on FreeBSD 3.4 < 1.5s < 2.5 days
(cachedir mounted as async, 9G)

d. squid 2.3 on FreeBSD 3.4 < 1.5s < 2 days
(cachedir soft-update, 9G)

Moreover, c & d 's cache miss time may fluctuate to 3 or 4 sec
sometimes. The tps of disks of b, c & d are much higher than that of a.
If I use top to watch the CPU usage, b, c & d have much higher
percentage of user than a. b, c & d have a very small %age of system
usage. a is slowest machine (Pentium 133 or 166). All of them have
NMBCLUSTER set at 4000. All of them should have enough file descriptor
too.

It seems to be something related to disk io. Are there something
special in FreeBSD 3.x? Do anyone have similar observation? Thanks a
lot.

So K T, CUHK
Received on Tue Jul 18 2000 - 21:56:54 MDT