In addition to that, even if it does have there is a high possibility of being used for intensive GPGPU calculations. -------- Original Message -------- On 14 Oct 2022, 18:03, Udo Grabowski (IMK) wrote:
> On 14/10/2022 16:51, Thijs Cramer wrote: > I've been searching the GitHub > Repository and the Mailing list, but couldn't > find any discussion about > this. > I know it's probably silly, but I would like to understand the > workings. > > Let's say one could offload the Checksumming process to a > dedicated GPU. This > might save some amount of CPU, *but* might increase > latency incredibly. > > To my understanding ZFS uses the Fletcher4 Checksum > Algorithm by default, and > this requires a pass of the data in-memory as it > calculates the checksum. If we > skip this step, and instead send the data to > the GPU, that would also require a > pass of the data (no gains there). > > > The actual calculation is not that hard for a CPU it seems, there are > specific > SIMD instructions for calculating specific Checksums, and after a > quick pass > over the code, it seems they are already used (if available). > > > I think the only time that a GPU could calculate checksums 'faster', is > with a > form of readahead. > If you would pre-read a lot of data, and dump > it to the GPU's internal memory, > and make the GPU calculate checksums of > the entire block in parallel, it might > be able to do it faster than a CPU. > > > Has anyone considered the idea? A typical ZFS server simply does not have > a GPU. -- Dr.Udo Grabowski Inst.f.Meteorology & Climate Research IMK-ASF-SAT > http://www.imk-asf.kit.edu/english/sat.php KIT - Karlsruhe Institute of > Technology http://www.kit.edu Postfach 3640,76021 Karlsruhe,Germany > T:(+49)721 608-26026 F:-926026 ------------------------------------------ > openzfs: openzfs-developer Permalink: > https://openzfs.topicbox.com/groups/developer/T2be6db01da63a639-Mdbb91bfa30ea2cdfdf9e24db > Delivery options: https://openzfs.topicbox.com/groups/developer/subscription ------------------------------------------ openzfs: openzfs-developer Permalink: https://openzfs.topicbox.com/groups/developer/T2be6db01da63a639-M729ffb93eba9729ad028c8c8 Delivery options: https://openzfs.topicbox.com/groups/developer/subscription
