This presentation discusses the myriad of challenges involved in getting to true Petaflop performance, including the CPUs, memory, interconnect, and software.

Conventional QoS mechanisms have focused primarily on providing better than normal service for some flows over others. With networks moving to much higher speeds and reasonable provisioning, best efforts access to network resources is adequate for common applications except when a belligerent flow attempts to consume an excessive amount of bandwidth. Any mechanism that attempts to contain such a flow must be able to operate at wirespeed in hardware. In this environment, conventional QoS mechanisms are not sufficient, either because they do not have mechanisms to contain these belligerent flows or because they are not practical to implement in hardware. In this paper we describe dynamic buffer limiting (DBL), a buffer and queue management mechanism designed to recognize and handle belligerent flows at very high speed and suitable for hardware implementation.

A frame buffer architecture is presented that reduces the overhead of frame buffer updating by three means. First, the bit-map memory is (x,y) addressable, whereby a string of pixels can be accessed in parallel. Second, the pixel-change operation is performed by hardware in a single read-modify-write cycle. Third, multiple objects in the frame buffer are addressable simultaneously by a set of address registers. The remaining task of generating (x,y) addresses and providing new data can be managed rapidly by current microprocessors or DMA-devices.With a modest expenditure of hardware, this architecture eliminates all the bit-shifting, bit-masking, and bit-manipulation conventionally associated with frame buffer graphics, while retaining the full generality of user-programmable control. The particular implementation described allows raster manipulation at full bit-map memory bandwidth. It can paint a 16×16 pixel character into the frame buffer in 16 microseconds and can modify a 1024×1024 pixel raster in 64 milliseconds.