Using Xperf to Track I/O
Back in December when I was working on the Places branch, I was using Xperf quite a bit to try and figure out why we were regressing certain performance tests. Xperf is an incredibly powerful tool, but it’s really hard to get it to do what you want sometimes. This is largely due to the fact that the documentation isn’t great, and there appears to be wrong information on the Internet (from blogs, which tend to be more useful than the documentation).
I cared about getting information about hard faults, file I/O, and disk I/O to see if patterns changed with my work. In order to accomplish this, I started Xpef like this (from an admin console):
xperf -start "NT Kernel Logger" -on PROC_THREAD+LOADER+HARD_FAULTS+FILE_IO+FILE_IO_INIT+DISK_IO -stackwalk FileWrite+FileRead+FileFlush -MaxBuffers 1024 -BufferSize 1024 -f output.etl
The first list options after -on is a list of providers. To see the list of installed kernel providers on your system and what they do, open up a command prompt, and run xperf -providers K.
The options after -stackwalk tells Xperf to get call stacks for certain events. The full list of events supported can be found here. I found it very difficult to get stacks, and if you are on a 64-bit version of windows, you have an extra hoop to jump through. I was actually never able to get stacks from an optimized build with symbols, so I ended up just using debug builds when I needed stacks, and opt builds when I wanted good numbers for everything else.
The -MaxBuffers and -BufferSize arguments were useful to prevent events from being dropped (if Xperf doesn’t have enough memory set aside to record an event, it just drops it). You can tweak those values to your needs, but the values I used should be fine.
Once I ran that command in my console, I’d perform the test I wanted to get data on. Upon completion, Xperf needs to be told to stop, and then have it merge (merging may be unnecessary when you only use kernel providers, but I never tested this theory):
xperf -stop "NT Kernel Logger"
xperf -merge output.etl output_final.etl
You can now open output_final.etl to examine the data you just gathered!
Highlight Warnings in Make
Curtis just gave me this incredibly handy piece of code that higlights errors and warnings in make output. Now, when I’m building, all the warnings are highlighted in yellow, and the errors in red. Just put the following in your bash profile script:
make()
{
pathpat="(/[^/]*)+:[0-9]+"
ccred=$(echo -e "\033[0;31m")
ccyellow=$(echo -e "\033[0;33m")
ccend=$(echo -e "\033[0m")
/usr/bin/make "$@" 2>&1 | sed -E -e "/[Ee]rror[: ]/ s%$pathpat%$ccred&$ccend%g" -e "/[Ww]arning[: ]/ s%$pathpat%$ccyellow&$ccend%g"
return ${PIPESTATUS[0]}
}
Of course, improvements and more ideas welcome! Thanks goes to Curtis for this!
I’m in a podcast!
A little while ago I got interviewed by Anthony Bryan from the metalink project. I feel sorry for him because it took me several long months to actually get the time to sit down and talk to him. Anyway, you can check out the podcast here. They used an old facebook photo of mine, so, uh, pardon the odd image of me. I figured it could be worse though.
It’s worth a listen though. I talk about some of the features of the new download manager (old news now, but he ask for this interview a while ago…), how I got involved with the Mozilla project, and a few other interesting tidbits including what I’ve currently been working on. There is other interesting things in there too!
Another new release? Why!?!
Well, WordPress has seen fit to release version 2.2. Now I have to decided if I want to upgrade now, or wait awhile. So, I ask you all this – is it worth upgrading, or should I stay on the 2.1 path for now (which is up to date for any of you would be hackers)?
Secure PHP on the Web
PHP is a powerful and easy language to learn. As a developer, you must use that power in a safe and effective manner. While being easy to learn means that it is easy to pick up, it also means that you may not have any experience with writing secure code. Writing secure code is a must, however, if you do not want your server to be compromised, user data stolen, your site destroyed, or quite possibly worse. In this article, you will learn about writing more secure PHP code.
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