Archive
Posts from 2005
Nixing the default Apache htdocs content
If you have the default Apache page installed on your web server, then mod_negotiate is going to be helpful and try to serve the content in the flavor and language your browser prefers. This of course comes at a hefty cost: I came across this while looking for the busiest functions in Apache (this of course is not the case with normal pages).
$ read more →Most common cause of memory failures
While reading through some Fujitsu documentation I came across the following: "Soft errors were formerly caused by alpha particles in the IC housing. This can now be precluded for the most part by an improved IC housing. Radioactive gamma radiation from solar eruptions is now the main cause of soft errors. In all probability, pure soft errors do not lead to uncorrectable multi-bit errors in a memory chip…
$ read more →Unmangling apxs and mod_deflate
I had a boat load of fun today debugging apxs and apr-config. The issue I was debugging came about when I decided to use mod_deflate to compress text, xml and style sheets on my web server. Since mod_deflate wasn't built when I had originally configured Apache, I thought I would fire up apxs to build the Apache module: W00t! The module built, so I installed it and tried to fire up Apache: Ack…
$ read more →Profiling Apache modules with DTrace
While poking around the Apache source code this weekend, I started to wonder which Apache modules consumed the most CPU time servicing HTTP requests. Since I had Apache installed on a Solaris 10 box, I threw together a D script named apachemoduleprof to answer this question: After running this a few times, I noticed that the httpd core along with a few other modules consumed most of the CPU time. To see which functions were the busiest in each module, I threw together the apachemodulefunctime D script: This example shows each function that is called in the mod_log_config Apache module, and provides a timestamp from the function entry to the function exit. This was super useful information, but I also wanted to see which functions were called from mod_log_config…
$ read more →USENIX LISA 2005 roundup
I just got back from LISA 2005, and had a blast in San Diego! As with every conference I attend, there were some key highlights: Don Bailey did an awesome presentation on 802.11 security, and showed just how difficult it is to secure wireless networks. Matt Blaze showed numerous flaws in wiretapping technologies (I had no idea what A C-tone was prior to his talk). Dan Kaminsky showed how to correlate DNS data and provided the coolest realtime network interaction demo EVER…
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