Micro stuttering
Encyclopedia
Micro stuttering is a term used in computing to describe a quality defect
inherent to multi-GPU
configurations, such as nVidia SLi
and AMD CrossFireX, using AFR
. It manifests as irregular delays between frames
rendered by the multiple GPUs, causing the instantaneous frame rate
of the longest delay to be significantly lower than the frame rate reported by benchmarking applications, such as 3DMark
, as they usually calculate the average frame rate over a longer time interval. In lower frame ratesUnder which frame rate the effects of micro stuttering becomes apparent varies depending on numerous variables and how sensitive the human test-subject is. The worst-case scenario would be that the frames from all GPUs finish rendering at the same time, in such a case the frame rate perceived by the viewer would be half of the reported average frame rate in the case of a dual-card configuration, and just a fourth in a quad-GPU configuration. when this effect may be apparent the moving video appears to stutter, resulting in a degraded gameplay
experience in the case of a video game, even though the frame rate seems high enoughThe generally accepted average frame rate for a smooth experience is 40 frame/s or higher. to provide a smooth experience. Single-GPU configurations do not suffer from this defect and can in some cases output a subjectively smoother video compared to a multi-GPU setup using the same video card
model.
The effects of micro stuttering varies depending on the application and driver
optimizations. It remains an issue with both nVidia- and AMD-based multi-card setups as of September 2011, however nVidia's SLI solution is less affected by the phenomenon for dual-GPU setups. Beyond dual-GPU setups, CrossFireX/SLI setups do not seem to be affected by micro-stuttering; the frame rate variability in a three-way CrossFireX setup is just as small as what is achieved by a single GPU.
Software bug
A software bug is the common term used to describe an error, flaw, mistake, failure, or fault in a computer program or system that produces an incorrect or unexpected result, or causes it to behave in unintended ways. Most bugs arise from mistakes and errors made by people in either a program's...
inherent to multi-GPU
Graphics processing unit
A graphics processing unit or GPU is a specialized circuit designed to rapidly manipulate and alter memory in such a way so as to accelerate the building of images in a frame buffer intended for output to a display...
configurations, such as nVidia SLi
Scalable Link Interface
Scalable Link Interface is a brand name for a multi-GPU solution developed by NVIDIA for linking two or more video cards together to produce a single output...
and AMD CrossFireX, using AFR
Alternate Frame Rendering
Alternate Frame Rendering is a technique of graphics rendering in personal computers which combines the work output of two or more graphics processing units for a single monitor, in order to improve image quality, or to accelerate the rendering performance...
. It manifests as irregular delays between frames
Film frame
In filmmaking, video production, animation, and related fields, a film frame or video frame is one of the many still images which compose the complete moving picture...
rendered by the multiple GPUs, causing the instantaneous frame rate
Frame rate
Frame rate is the frequency at which an imaging device produces unique consecutive images called frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems...
of the longest delay to be significantly lower than the frame rate reported by benchmarking applications, such as 3DMark
3DMark
3DMark is a computer benchmarking tool created and developed by Futuremark Corporation to determine the performance of a computer's 3D graphic rendering and CPU workload processing capabilities. Running 3DMark produces a 3DMark score with higher numbers indicating better performance...
, as they usually calculate the average frame rate over a longer time interval. In lower frame ratesUnder which frame rate the effects of micro stuttering becomes apparent varies depending on numerous variables and how sensitive the human test-subject is. The worst-case scenario would be that the frames from all GPUs finish rendering at the same time, in such a case the frame rate perceived by the viewer would be half of the reported average frame rate in the case of a dual-card configuration, and just a fourth in a quad-GPU configuration. when this effect may be apparent the moving video appears to stutter, resulting in a degraded gameplay
Gameplay
Gameplay is the specific way in which players interact with a game, and in particular with video games. Gameplay is the pattern defined through the game rules, connection between player and the game, challenges and overcoming them, plot and player's connection with it...
experience in the case of a video game, even though the frame rate seems high enoughThe generally accepted average frame rate for a smooth experience is 40 frame/s or higher. to provide a smooth experience. Single-GPU configurations do not suffer from this defect and can in some cases output a subjectively smoother video compared to a multi-GPU setup using the same video card
Video card
A video card, Graphics Card, or Graphics adapter is an expansion card which generates output images to a display. Most video cards offer various functions such as accelerated rendering of 3D scenes and 2D graphics, MPEG-2/MPEG-4 decoding, TV output, or the ability to connect multiple monitors...
model.
The effects of micro stuttering varies depending on the application and driver
Device driver
In computing, a device driver or software driver is a computer program allowing higher-level computer programs to interact with a hardware device....
optimizations. It remains an issue with both nVidia- and AMD-based multi-card setups as of September 2011, however nVidia's SLI solution is less affected by the phenomenon for dual-GPU setups. Beyond dual-GPU setups, CrossFireX/SLI setups do not seem to be affected by micro-stuttering; the frame rate variability in a three-way CrossFireX setup is just as small as what is achieved by a single GPU.
See also
- RenderingRendering (computer graphics)Rendering is the process of generating an image from a model , by means of computer programs. A scene file contains objects in a strictly defined language or data structure; it would contain geometry, viewpoint, texture, lighting, and shading information as a description of the virtual scene...
- Video cardVideo cardA video card, Graphics Card, or Graphics adapter is an expansion card which generates output images to a display. Most video cards offer various functions such as accelerated rendering of 3D scenes and 2D graphics, MPEG-2/MPEG-4 decoding, TV output, or the ability to connect multiple monitors...
- Graphics processing unitGraphics processing unitA graphics processing unit or GPU is a specialized circuit designed to rapidly manipulate and alter memory in such a way so as to accelerate the building of images in a frame buffer intended for output to a display...
(GPU) - AMD CrossFireX
- nVidia SLiScalable Link InterfaceScalable Link Interface is a brand name for a multi-GPU solution developed by NVIDIA for linking two or more video cards together to produce a single output...
External links
- Micro-Stuttering And GPU Scaling In CrossFire And SLI – Tom's Hardware
- Inside the second: A new look at game benchmarking – Tech Report