Statistics Bar Guide
What is the Statistics Bar?
The Statistics bar presents an detailed list of information about the performance of your computer and the Second Life world. While the sheer amount of information can be confusing, knowing what to look for can tell you a lot about what's going on in Second Life.
How do I view the Statistics Bar?
Select View > Statistics Bar from the top of the Second Life window.
What does all this stuff mean?
We'll go through each section in detail.
Displays basic information about your Second Life performance. Click on the word Basic to hide or display this panel.
FPS: The number of times per second your computer is redrawing(or refreshing) what's on the screen. Higher numbers are better. A framerate between 15-30 frames per second (FPS) is about as smooth as broadcast television.
Bandwidth: How much data is being transferred between your computer and the Second Life world. This number varies wildly depending on what bandwidth settings you've used, where you are inworld, what's going on, and whether you're still loading some things (objects/textures/etc) that are in your field of view. If bandwidth is 0kbps, something may be wrong (you may be partially disconnected).
Packet Loss: The amount of data being lost as it travels between your computer and the server. Any nonzero packet loss is bad; packetloss above 10% is very bad. Packet loss might be caused by a dying server (in which case everyone in the region would be experiencing it), a bad connection between you and Second Life (possibly a bad router between your ISP and Second Life, or congestion at your ISP), or problems on your local network (wireless networking, or internet security or firewall software on your computer).
Ping Sim: How long it takes data to go from your computer to the region you're currently in. This is largely dependent on your connection to the Internet. If Ping Sim is high but Ping User is not, the server might be having problems.
Displays lots of nitty-gritty details about your Second Life performance. Most of these details are less useful than Basic or Simulator. Click on the word Advanced to hide or display this panel.
Displays information related to drawing the Second Life world.
KTris Drawn: (per frame) Computer-generated 3D objects are built out of triangles (the basic geometric shape). This is a count of the number of triangles, or "tris", in each frame of the current scene.
KTris Drawn: (per second) This is a count of the number of triangles ("tris") drawn every second.
Total Objs: The number of objects currently in view, which includes:
- Terrain patches
- Particle groups
- Water patches
New Objs: The number of objects being downloaded per second.
Detailed information on the textures currently in use. Click on the word Texture to hide or display this panel.
Count: The number of unique textures loaded by the viewer.
Raw Count: The number of textures loaded by the viewer that have been paged out (exist in application memory and not driver memory).
GL Mem: The amount of driver memory consumed by textures.
Raw Mem: The amount of application memory consumed by textures.
Bound Mem: The memory size of all textures bound for rendering per frame.
Information coming soon!
Displays statistics for the region (simulator) you're currently in. Click on the word Simulator to hide or display this panel.
There was a major redesign in how the simulator operates in the 1.7 release. In previous releases, the simulator would run as quickly as it could, and then only run physics at 45 frames per second. This meant that the simulator would run at very high frame rates (in the thousands) when there was no load, which was not a very efficient mode of operation. In addition, when there were a lot of scripts or many people connected to the simulator, the frame rate would drop and fluctuate as many scripts attempted to run on every frame. In the following discussion an "agent" is either a user inside of a given simulator region (a "main agent") or a user in a neighboring simulator region (a "child agent"). Any user who can see objects inside a simulator region increases the load on that simulator. The simulator scheduler was redesigned so that it now attempts to run at a fixed frame rate which is the same as the physics frame rate. Instead of the simulator frame rate changing as load changes, the simulator spends more or less time running LSL scripts each frame. This means that if there are a large number of scripts on the simulator, the frame rate will stay the same, but all of the scripts will run less frequently. Only in situations of particularly heavy physics load or large numbers of agents will the simulator framerate drop from 45 frames/second. In addition, there was a major redesign of the logic used to transmit objects from the simulator to the viewers (called the interest list). The resulting improvements reduce the amount of load incurred when there are many agents on the same simulator. The combination of the above two changes should result in significantly decreased "lag", and improved performance when many agents are on a simulator.Reading the numbers
Because of the changes to the simulator execution model, most of the statistics which were used to evaluate simulator performance have been changed. Below is a detailed summary of what the new simulator performance statistics mean. All of the numbers below are for simulators running on a single simulator per CPU. On simulators which are not running in this fashion (water simulators, etc), these number will be different. The following are the different statistics in the Simulator section of the statistics pane (accessed via Ctrl-shift-1 or the Advanced menu):
- Time Dilation - The physics simulation rate relative to realtime. 1.0 means that the simulator is running at full speed; 0.5 means that physics are running at half-speed.
- Sim FPS - The simulator frame rate. This should now always be the same as the physics frame rate -- 45.0 when things are running well.
- Physics FPS - The frame rate at which the physics engine is running. This should normally be at or near 45.0.
- Agent Updates/Sec - The rate at which agents on this simulator are being updated. Normally 20 updates a second, this will decrease if the simulator has a large number of agents on it.
- Main Agents - The number of agents (users) who are on this simulator.
- Child Agents - The number of agents who are not on this simulator, but can see it.
- Objects - The total number of primitives on the simulator. This value does not include primitives being worn as attachments.
- Active Objects - The number of objects containing active scripts on the simulator. This value does not include scripts inside attachments, unless the attachment wearer is sitting on a scripted object.
- Active Scripts - The number of running scripts that are currently on the simulator, including scripts attached to agents and objects.
- Script Perf - Number of LSL opcodes being executed a second by the simulator. Note that this is the number of ACTUAL instructions executed in the last second, not the theoretical maximum opcodes/second. If your simulator is not running very many scripts, this number will be low even if performance is good.
- Packets In - UDP packets being received by the simulator.
- Packets Out - UDP packets being sent by the simulator.
- Pending Downloads - Number of asset downloads to the simulator that are pending. If this is greater than 1, this means that you may see delays in viewing notecards or scripts, and rezzing objects.
- Pending Uploads - Number of current uploads of asset data pending. If this number is non-zero, this means that there may be performance issues when attempting to teleport.
- Total Unacked Bytes - The size of the reliable packet data sitting on the server waiting to be acknowledged. A large number may indicate a thin pipe or other possible problems between the viewer and the sim.
The following are the different times listed in the Time section of the Statistics bar. Click Time to hide or display this panel.
- Total Frame Time - The sum of all time values listed below it, this measures how much time it takes the simulator to run everything that the simulator is trying to do each frame.
- < 22 ms - The simulator is healthy, everything is running as fast as it can, and more scripts can be added without reducing the performance of individual scripts.
- approx. 22 ms - The simulator is healthy, but there are probably a lot of scripts and agents on the simulator, meaning that script execution is being slowed down in order to maintain the simulator frame rate.
- > 22 ms - The simulator is experiencing severe load, either due to physics or a large number of agents, such that even by slowing down script execution it is impossible to compensate. The simulator frame rate has been reduced as a result.
- Net Time - The amount of time spent responding to incoming network data.
- Sim Time (Physics) - The amount of time that frame spent running physics simulations. In general, this should be less than 5 milliseconds.
- Sim Time (Other) - The amount of time that frame spent running other simulations (agent movement, weather simulation, etc.)
- Agent Time - The amount of time spent updating and transmitting object data to the agents.
- Images Time - The amount of time spent updating and transmitting image data to the agents.
- Script Time - The amount of time spent running scripts.