Author: eilemann@gmail.com
State:
- Implemented in 0.2
- Statistics Overlay implemented in 0.5.1
This document describes the first evolution of the statistics interface. With new requirements, for example load balancing, this interface will evolve much further.
Specification
Statistics are measured in milliseconds since the configuration was
initialized. On each node, the global configuration clock is reset at the same
time by the server during Config::init. Each statistic event
records the originator's (channel, window or config) unique identifier.
Statistics are enabled per entity using an attribute hint. The hint determines how precise the gathered statistics are. When set to fastest, the per-frame clock is sampled directly when the event occurs. When set to nicest, all OpenGL commands will be finished before sampling certain events, which incurs a performance penalty. The default setting is fastest in release builds, and nicest in debug builds.
The events are processed by the channel's and
window's processEvent. The default implementation sends these
events to the config. The default implementation
of Config::handleEvent sorts the received events per frame and
per originator. When a frame has been finished, the events are pushed to the
local (app-)node for visualization.
File Format
global
{
EQ_CHANNEL_IATTR_HINT_STATISTICS off | fastest [on] | nicest
}
channel
{
attributes
{
hint_statistics off | fastest [on] | nicest
}
}
API
New Types
struct StatEvent
{
public:
enum Type
{
CHANNEL_CLEAR,
CHANNEL_DRAW,
CHANNEL_ASSEMBLE,
CHANNEL_READBACK,
CHANNEL_TRANSMIT,
CHANNEL_COMPRESS,
TYPE_ALL // must be last
};
Type type;
uint32_t objectType;
uint32_t objectID;
float startTime;
float endTime;
};
New Functions
float Pipe::getFrameTime() const; void Pipe::addStatEvent( const StatEvent& event );
