קולוקוויום וסמינרים

While zero-shot diffusion-based compression methods have seen significant progress in recent years, they remain notoriously slow and computationally demanding. We present an efficient zero-shot diffusion-based compression method that runs substantially faster than existing methods, while maintaining performance that is on par with the state-of-the-art techniques. Our method builds upon the recently proposed Denoising Diffusion Codebook Models (DDCMs) compression scheme. Specifically, DDCM compresses an image by sequentially choosing the diffusion noise vectors from reproducible random codebooks, guiding the denoiser's output to reconstruct the target image. We modify this framework with Turbo-DDCM, which efficiently combines a large number of noise vectors at each denoising step, thereby significantly reducing the number of required denoising operations. This modification is also coupled with an improved encoding protocol. Furthermore, we introduce two flexible variants of Turbo-DDCM, a priority-aware variant that prioritizes user-specified regions and a distortion-controlled variant that compresses an image based on a target PSNR rather than a target BPP. Comprehensive experiments position Turbo-DDCM as a compelling, practical, and flexible image compression scheme.

A "named page" is a memory page whose content originates from and is backed by a file. Because named pages are regularly read from and written to persistent storage, filesystems strive to preserve file content contiguity, thereby enabling sequential I/O, which can be much faster than random I/O. No analogous effort to preserve contiguity exists for "anonymous pages," which hold unnamed data such as stack or heap bytes. Consequently, swapping a region of anonymous pages in or out can be much slower than reading or writing a region of named pages.

We observe (1) that the main advantage of the existing swap mechanism is high swap area utilization, since any anonymous page can be placed at any offset within the swap file, so there is no fragmentation; but (2) that secondary storage is commonly underutilized, so the cost of random I/O may be unwarranted. We therefore propose "named swapping," which associates each anonymous region with its own (swap) file and thus benefits from the underlying filesystem's efforts to maintain contiguity, improving swap performance by up to an order of magnitude. A key challenge we address is anonymous pages shared across multiple regions due to fork-based copy-on-write.