If you don’t know what SystemTap is – it’s the Linux world’s attempt to build Solaris DTrace style safe dynamic instrumentation into Linux kernel.
I’m not going into religious discussions which one is better here, I have used both SystemTap and DTrace successfully for diagnosing low level issues inside OS kernel, so both are good enough for me :)
The problem with SystemTap though has been that it’s not production quality, it’s rather been a technology preview.
But with RHEL 5.4 part of it has changed, Redhat says following in this article:
SystemTap is no longer a technology preview, and now has production support. Red Hat recommendeds that users run scripts on development machines before deployment in production environments. Since SystemTap is an optional diagnostic tool, users can easily stop using it in the event of a problem. Options such as
-g for Guru mode, and
-D* allow users to disable several security checks. Scripts using these options may not be supported.
Red Hat plans to fix problems in SystemTap, or the Linux kernel, as they arise in connection with new scripts. In some cases, a fix may include extending the blacklist for known areas of the Linux kernel that are unsafe to probe. All scripts that use probes targeting blacklisted areas will need to be revised.
SystemTap users are advised to upgrade to this version.
So, at least officially, SystemTap is now supported by Redhat. Well at least as long as you’re not doing crazy stuff with the -g option, the geek mode ;-)
I would still be very careful before using any SystemTap in production, in fact, in critial environments I wouldn’t run it at all, unless there is no other option (and you’re prepared to get a crash + kernel panic).
However the significance of this note is that SystemTap is accepted for production by Redhat in principle. So now it’s just matter of time until it gets stable and widely used enough to be as practical and useful as DTrace is on Solaris.