On Wed, May 07, 2025 at 02:43:21PM +0200, David Sterba wrote: > On Tue, May 06, 2025 at 04:38:11PM +0100, Cabiddu, Giovanni wrote: > > Hi David, > > > > I've resumed work on this, now that I have all necessary dependencies to > > offload ZSTD to QAT. > > > > On Mon, Apr 29, 2024 at 04:41:29PM +0100, David Sterba wrote: > > ... > > > I'd skip the style and implementation details for now. The absence of > > > compression level support seems like the biggest problem, also in > > > combination with uncondtional use of the acomp interface. > > Regarding compression levels, Herbert suggested a new interface that > > would effectively address this concern [1]. > > It seems to be sufficient for passing the level from filesystem to > crypto layer. > > One thing I'm not sure is considered is that zstd has different > requirements for workspace size depending on the level. In btrfs this is > done in zstd_calc_ws_mem_sizes(). > > > > We'd have to enhance the compression format specifier to make it > > > configurable in the sense: if accelerator is available use it, otherwise > > > do CPU and synchronous compression. > > For usability, wouldn't it be better to have a transparent solution? If > > an accelerator is present, use it, rather than having a configuration > > knob. > > > > In any case, I would like to understand the best way forward here. I > > would like to offload both zlib_deflate and ZSTD. However, I wouldn't > > like to replicate the logic that calls the acomp APIs in both > > fs/btrfs/zlib.c and fs/btrfs/zstd.c. > > This looks doable, acomp_comp_pages() from your patch could work for > both, the only difference is the parameter to crypto_alloc_acomp() and > eventually the level. > > Otherwise, how to go forward with that. I think we'd need to get a few > iterations staring from what you have, with added support for the levels > and then we'll remove/replace the problematic parts like the numerous > allocations. > > As the first step, please send an update with the acomp levels added to > zlib callbacks, so it works in normal conditons with all the > allocations. > > We'll need to move repeatedly used structures to the workspaces so that > will be the second step. Once we settle on someting reasonable we can > extend it and add zstd support. Thanks David. I like the incremental approach. I'll be sending a new version that is rebased on top of 6.15-rc. This update will include the addition of compression levels to zlib-deflate and will utilize folios instead of pages. We can proceed from there. Regards, -- Giovanni
