On Fri, Sep 23, 2011 at 12:06 AM, Pandu Poluan <pa...@poluan.info> wrote: > Saw this on the pfSense list: > > http://shader.kaist.edu/packetshader/ > > anyone interested in trying?
I see a lot of graphs touting high throughput, but what about latency? That's the kind of stuff that gets in my way when I'm messing with things like VOIP. My first thought when I saw they were using a GPU for processing was concerns about latency: 1) RTT between a video card and the CPU will cause an increase in latency from doing processing on-CPU. Maybe DMA between the video card and NICs could help with this, but I don't know. Certainly newer CPUs with on-die GPUs will have an advantage here. 2) GPGPU coding favors batch processing over small streams. That's part of its nature, after all. That means that processed packets would come out of the GPU side of the engine in bursts. They also tout a huge preallocated packet buffer, and I'm not sure that's a good thing, either. It may or may not cause latency problems, depending on how they use it. They don't talk about latency at all, except for one sentence: "Forwarding table lookup is highly memory-intensive, and GPU can acclerate it with both latency hiding capability and bandwidth." -- :wq
