sysctl

以前一直以为不行的，今天仔细看了一下manpage：

如欲让sysctl之后能使用tab补齐，则应使用：

complete sysctl ’n/*/`sysctl -Na`/'

试了一下，不错！

最近 current 邮件列表讨论的很凶的一个问题是，MySQL很不理性地在每一个I/O操作时都调一次time()。这一操作在FreeBSD上面相当的昂贵(为了保证精度)，而Linux采取了许多优化(有些是牺牲精度的)措施，因而性能差距越来越大。

于是有一个人在FreeBSD上做了试验，说改一下默认的时钟能够将性能提高6倍……不带这么玩的，ft……

BTW. clive也测了一下，在他机器上结果是：

You may have noticed that FreeBSD by default does not allow many programs to play sound at same time. For instance, you generally can not hear GAIM sound when you are hearing MP3.

Fortunately, this can be resolved if you have read the documentations. Now I write here so you can also Google it :-)

Add a single line into /etc/sysctl.conf:

hw.snd.pcm0.vchans=16

Then, reboot (or if you are careful enough, shut down all programs that is using sound subsystem, then run /etc/rc.d/sysctl restart)

Don Lewis (truckman@) has committed a fix for the sysctl spinning problem I mentioned here some days before. Currently, beastie.frontfree.net is running a workaround which made it possible to skip the deadlock, however, will not guarantee the correct result.