Effects of Changing vfs.ufs.dirhash_maxmem in FreeBSD

I have a busy web frontend server many files in a single directory. The server is running FreeBSD 8 amd64. Here is the result of changing the sysctl vfs.ufs.dirhash_maxmem to 67108864. Note the change in system (red) area. The vertical arrow shows when the change was made:

Recovering from a terminal full of gibberish

Have you ever accidentally tried to view a binary file and your terminal started spewing all sorts of weird characters?

$ cat /etc/localtime
???w?qˈ???#?p?a???u??@???U?? ???5?????????????
?p@?0?p?'? ?p ??
?u???????t??tyV?iVY8?I89?)"7?p???p?????p?܀??p v!??p"U?#j??$5?%J??&?'*??'?р)

The solution is to type reset and hit return.

▒⎼±␋⎺⎻␊# ⎼␊⎽␊├
Erase set to backspace.

There. All better.


Performance presentation, Des Moines Web Geeks

Matt Nuzum, the webmaster of, invited me to speak at the Des Moines Web Geeks meeting last night. The venue, Impromptu Studios, was a bit hard to find. There were no signs for Impromptu Studios, but after lurking in dark alleyways for a while I eventually discovered what should have been obvious from the beginning: enter the furniture store with the "Closed" sign on the front and go up the stairs past the disused lavatory with a sign on the door saying "Beware of the Leopard."

The group was great and we talked for about an hour and half about bottlenecks and optimization. I even went home with a Django book!

Since this was a diverse group I tried to talk about things that everyone has to deal with (bottlenecks for storage, network, memory and CPU) rather than anything Drupal-specific.

As promised, last night's slides: Performance, Scalability on the Server Side (PDF, 1MB).

Watching traffic on FreeBSD

Ben Wong at MostlyGeek pointed out that a great way to watch traffic on FreeBSD is the command systat -ifstat 1 which shows:

                    /0   /1   /2   /3   /4   /5   /6   /7   /8   /9   /10
     Load Average   ||   

      Interface           Traffic               Peak                Total

            lo0  in      0.000 KB/s          0.000 KB/s            4.122 MB
                 out     0.000 KB/s          0.000 KB/s            4.122 MB

           bge0  in      6.181 KB/s         36.944 KB/s            1.666 GB
                 out   110.521 KB/s        670.040 KB/s            3.444 GB


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