Frequently Asked Questions (FAQ)

General

  1. How long does the evaluation license last?
  2. What does buying a license get me?
  3. Can RotateRight help me improve the performance of my code or system?
  4. What does the name "RotateRight" mean?
  5. How will my personal information be used?

Technical

  1. My favorite flavor of Linux isn't on the list of supported distributions. Do you support it?
  2. My processor isn't in the list of supported hardware, but works with oprofile. Do you support it?
  3. What's the difference between the RotateRight kernel modules and the oprofile kernel module?
  4. Why didn't rrprofile/rrnotify load on startup?
  5. Why did Zoom crash on startup?
  6. Can I install Zoom without using the GUI?
  7. Can I run Zoom under VMWare?
  8. Can I run Zoom under Xen or KVM?
  9. Can I run Zoom i386 on x86-64 Linux distributions?
  10. Why don't I get full backtraces when profiling on x86-64?
  11. Why do I get misleading backtraces when profiling on x86-64?
  12. Why did Zoom fail with the error message "version 'GLIBC_2.3.3' not found"?


General

1. How long does the evaluation license last?

30 days.

2. What does buying a license get me?

A license gives you high-priority tech-support, and it gets you enhancements and bug fixes for the lifetime of the current product release. You also get the satisfaction of helping a small software company keep making great products!

You can use a single license to target more than one machine using remote profiling, and you're free to move your copy of Zoom to new machines. If you're a group or company with multiple users, please purchase a license for each user.

3. Can RotateRight help me improve the performance of my code or system?

Certainly! We have plenty of experience in general and platform-specific code optimization, and we're happy to take on contract projects. Send us a note and let us know what you have in mind.

4. What does the name "RotateRight" mean?

RotateRight is both a low-level bit operation and what we hope to do for your code: change it for the better.

5. How will my personal information be used?

Please refer to our privacy policy.

Technical

1. My favorite flavor of Linux isn't on the list of supported distributions. Do you support it?

Zoom should run on other Linux distributions based on kernel 2.6.15 or later. The 2.6.9 kernel is also supported. Zoom will work with some limitations on older Linux kernels. To install on other distributions, refer to the Manual Installation section in the release notes.

2. My processor isn't in the list of supported hardware, but works with oprofile. Do you support it?

At this time we can't provide full support for every CPU, but try using the oprofile compatibility driver included with Zoom. Let us know what hardware you're interested in, and we may be able to add support for it.

3. What's the difference between the RotateRight kernel modules and the oprofile kernel module?

The rrprofile kernel module is based on oprofile, but adds support for time stamps, disables nap during sampling and supports both PMC and timer interrupt based sampling without reloading the kernel module. In addition, rrnotify reduces the overhead of profiling by deferring the gathering of process memory maps until after profiling is finished (when possible).

4. Why didn't rrprofile/rrnotify load on startup?

If SELinux is set to "Enforcing," it will prevent the kernel modules from loading on startup. To disable SELinux, edit /etc/selinux/config and set SELINUX=disabled.

5. Why did Zoom crash on startup?

If you're running on a fresh openSUSE 10.3 install, bug-buddy must be removed or updated. If that's not it, send us your system info and any crash report logs, and we'll figure it out.

6. Can I install Zoom without using the GUI?

Absolutely - type "./<archive>.bin --text".

7. Can I run Zoom under VMWare?

Yes, Zoom can profile under VMWare with the "OS Timer" trigger. The only limitation is that backtraces cannot be collected using this trigger.

8. Can I run Zoom under Xen or KVM?

Zoom hasn't been tested under either of these virtualization solutions.

9. Can I run Zoom i386 on x86-64 Linux distributions?

Partially - refer to Running Zoom i386 (32-bit) on Linux x86-64 (64-bit) in the release notes.

10. Why don't I get full backtraces when profiling on x86-64?

By default, the gcc compiler on x86-64 Linux distributions omits the frame pointer during compilation. To enable the collection of full backtraces, you must recompile your x86-64 code with "-fno-omit-frame-pointer". Adding a frame pointer to normal code should have a very slight performance and size impact, but it sure makes debugging and profiling easier.

11. Why do I get misleading backtraces when profiling on x86-64?

Assume function A calls function B which in turn calls library L (A -> B -> L). If library L omits frame pointers, Zoom will show that A called L because the stack frame pointer and return address are not updated inside library L. If the library L is compiled with "-fno-omit-frame-pointer", the frame pointer and return address will be correctly updated.

12. Why did Zoom fail with the error message "version 'GLIBC_2.3.3' not found"?

Please unset the LD_ASSUME_KERNEL environment variable. We recommend that you remove all references to LD_ASSUME_KERNEL.

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