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Solaris DTrace To Be Ported to FreeBSD
daria42 writes "It looks like Sun's famous Dynamic Tracing tool - one of the best features in Solaris 10 - is getting ported to FreeBSD. Sun open-sourced the code back in January and it has been picked up by FreeBSD developer Devon O'Dell. The tool provides insanely great advanced performance analysis and debugging features for server software. Good to see some result come out of the Sun open-sourcing process." From the article: "O'Dell told ZDNet Australia the aim of the project -- which commenced a month ago -- was that all scripts and applications that utilised DTrace under its native Solaris environment should be able to run in FreeBSD with no changes. While FreeBSD's existing ktrace function was similar to DTrace, it was limited in scope, according to O'Dell. 'FreeBSD implements a somewhat similar facility for dynamically instrumenting syscalls for any given application,' he said."
I'm not sure how this benefits Sun, but something as awesome as this, I'm willing to assume it's altruism, and I appreciate it.
Nothing great was ever achieved without enthusiasm
It looks like a really useful tool. I wonder what the performance penalty is when the tool is turned off.
Do you need to instrument the calls you expect to profile? If so, how can you avoid taking that performance hit when deciding whether to perform the profiling or not, even when the profiler is off? It's still got to check the profiler level each time, doesn't it?
Jesus saved me from my past. He can save you as well.
Um, actually, quite a few people (myself included) use it on servers (and I use it on my laptop as well), and most of us are quite happy about this, and get quite upset when people blow us off as if the only real F/OS OS to use is GNU/Linux. You might actually like a BSD if you try it...
Why would this occasion a license change? It's a *port*, as in, the code will now run on more systems than it used to. Licensing doesn't have anything to do with that; it's still fundamentally the same codebase, so I'm sure the code will still be covered by the same licensing terms it already was released under.
To create a BSD-licensed version, someone would have to *clone* it, which is different from porting.
Cut that out, or I will ship you to Norilsk in a box.
For we that don't have a clue what DTrace is, here's what the has to say: DTrace allows to do performance tuning with applications and troubleshoot production systems--all with little or no performance impact. DTrace provides improved visibility into kernel and application activity, giving the user operational insights with which they can make performance gains..
The no performance penalty sounds really cool to me.
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"insanely great" is well known. In fact, it's in the Jargon File
Igor Presnyakov stole my hat
I'd be willing to bet there's a shitload of FreeBSD web servers out there, since I manage twelve of them, myself.
Linux has its uses and is great for many tasks, but only Gentoo comes close to the ports system and how well it manages software installation.
Either way, I'm hoping that yes, it will be ported to Linux as well, if it hasn't been already.
if you're referring to http://oprofile.sourceforge.net/news/, you're sadly mistaken. Realtime system profiling is very far behind on Linux compared to Solaris.
/dev/null - Sure you'll see abount 1% cpu utilization, but again, guess work at whats actually using IO.
Can you monitor how much network bandwidth each process uses? -- Sure you can see listening ports and IP traffic, and ntop is fantastic at showing what network bandwidth is used for (i.e. spotting p2p and IM traffic, eg). However if you have a trojen and you see suspecious network activity, there is a certain amount of guess work to try to find the process. Solaris will show exactly what process is making what connection where and the bandwidth it is using.
Can you monitor how much IO utilization each process has? -- No, only IO wait and CPU consumption which is normally enough, but say you have a script thats just reading all content on the disk and redirects it to
Sure you're usually right making an educated guess but system profiling is far ahead on Solaris.
A tool like this could really aid in finding all the bottlenecks. Benchmarks have become an embarrassment for FreeBSD as of late, and it is really sad to see that FreeBSD has fallen so far behind. Hopefully this could start to turn things around.
kprobes is not comparable to dtrace, to see a comparison between dtrace and kprobes check out
dtrace vs. krpobes
systemtap is in its infancy and being designed without safety as a priority, dtrace was created to be 100% safe to run anytime, even in production. systemtap is being made for the kernel hacker to debug the kernel. With possibly some userland probes and safety as an after thought. Sure they talk about safety as a goal. But as documented dtrace_usenix.pdf
dtrace was created from the start to be safe and secure. They even sacrafice some functionality to keep production servers safe. Systemtap is like building a bank they build the building, bring in the money, and desks, and machines, and promise that top of the line doors, windows and safe will top of the line and installed any day now.
As the guy porting DTrace, I want to clear up a few questions that appear frequently in the comments here. First, though, please be kind to the blog -- it's hosted on our (OffMyServer's) network, which is on a T1. I dunno how bad it got when the story was posted, but just for reference, it'd be nice to not have our network connection die.
:)
FAQ #1 seems to be about the license. Obviously, the CDDL is `viral' in the sense that changes in the code need to be provided under the same terms of the CDDL. In my understanding, this applies only to files in which modifications take place. Extension of something CDDL by adding extra files seems to not require those files to be released under the CDDL. That said, this is a porting effort, and most of the changes I will make will be inside CDDL-licensed files. Thus, anything imported will be under the CDDL. This does not require anything external files to be under the CDDL and thus it can be shipped with FreeBSD without `infecting' other files.
FAQ #2 seems to be whether Sun is happy about this or not. If you have read the article, you would have seen that I've been encouraged to work on this by Sun kernel engineers. Whether Sun as a whole is happy about this is not known to me, but everybody involved in getting it this far has been, so I'm not terribly worried about the rest.
FAQ #3 is about performance incurrences. Certain aspects of DTrace incur performance penalties, but only when DTrace is running. DTrace by itself is a library and a userland tool. All instrumentation is done dynamically and when DTrace is not instrumenting something, no performance hits happen whatsoever. When it is running, we have several advantages to other tools because (unlike e.g. truss) we are instrumenting single processes. Processes which are not being instrumented will not take any performance hits other than the fact that they have a bit less CPU usage since DTrace is instrumenting something.
How do you not take a performance penalty when the profiler is off? You must be root to run DTrace. When you instrument functions inside an application, this is done on-the-fly by rewriting the code that is being executed. When it is not being executed, nothing is being rewritten and it's not even looking to rewrite something. It's just some code resident in memory (in fact, modules are even loaded as needed). It sounds like it might be prone to security flaws, but keep in mind that this has been working in production for a while now.
When will this be in Linux? I don't know. I won't be working on it. I challenge _you_ to do this
Is this vaporware? No. I'm continuing development from about a week off (since I lost my development machine) this evening.
Feel free to ask more questions, I'll try to address them as I see them. But please refrain from bad-mouthing Sun or myself out of spite, jealousy, or whatever. I know it's fun to troll (if you're a troll), but the rest of us really don't appreciate it.
--Devon
www.sitetronics.com/wordpress
Is there any reason why I shouldn't look at FBSD as if it were a flavor of Linux? Yeah, it has a different kernel. I guess FBSD might be a little faster? That is what the benchmarks say, but the difference isn't staggering. I certainly don't notice. Is it more stable? I haven't had many problems with Linux that couldn't be blamed on cheap PC hardware.
Yes, a very important reason - FreeBSD is not Linux, just as surely as SCO UnixWare is not Solaris. Their codebase is certainly not the same, and in fact FreeBSD's code lineage dates back many years before Linux.
FreeBSD and Linux, being F/OSS systems, share a very large base of F/OSS software, so looking at kde on X on FreeBSD really won't appear that different from looking at kde on X on linux. I could just as well ask why anyone would want to use Linux when it just looks like a derivative of FreeBSD, which predates it. but that would not be a fair assessment because Linux is a seperate work built by another party. Yes, it is a unix-like system. Yes, it strives to adhere to POSIX standards. Yes, it runs all the same software. But no, it is a different system.
I have been using FreeBSD and NetBSD for many years, and where I work all of our stuff is on SuSE. In my opinion, SuSE is impossible to upgrade, its package system is inadequate, and shorewall is a lousy attempt at ip filtering. If I had my way I'd probably replace everything with FreeBSD. But did you notice somehting about the attitude of my opinions? Wasn't your first thought "Well gee, you use FreeBSD all the time and you've probably barely given SuSE Linux a shot?" If it was, you would be right. Because I learned to accomplish tasks in FreeBSD, I favor it - the same way I favor speaking in english over german because english is my native language. I'm sure if you sit down and think about it, when you picked up FreeBSD you tried to do things in the Debian idiom, expecting Debian results. But you didn't get them. So you're underwhelmed. It's natural, but please don't try to attribute it to FreeBSD being an inadequate copy of your favorite system, because that simply is a lie.
On the packages/ports system, I think you've really overdramaticized your plight with the BSD way-of-doing-things. First, you can cvsup the ports tree and compile from source. But you can also use pkg_add to add binary packages. If you don't want to fetch the package tarball yourself, you can use pkg_add's remote fetching feature. Simply pkg_add -r and you're on your way. It will take care of dependencies and the package database will record the package's information. You can also install portupgrade and use it to magically update a port and its dependencies when it is time to upgrade. It's not a difficult or time consuming system to use. I'm unfamiliar with Debian's package system, so I can't make any comments on it, but FreeBSD's package system has always been very useful fo me, and it gets more powerful all the time.
Overall, though, Linux and BSD really do feed from eachother's growth. What's good for one is good for the other. I may use FreeBSD, but that doesn't mean Linux is useless; and the opposite is true as well. All this bickering is really pointless because both projects will continue on in their own directions; some people will favor the one while some people will favor the other. It's simply a matter of preference
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