Messages in this thread | | | Date | Fri, 22 Sep 2023 16:40:26 +0200 | Subject | Re: [PATCH v5 0/5] Implement MTE tag compression for swapped pages | From | Alexander Lobakin <> |
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From: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Date: Fri, 22 Sep 2023 17:35:19 +0300
> +Cc: Olek, who internally is being developed something similar to your first > patch here.
Oh, thanks. The patch you mentioned properly implements cross-boundary accesses, mine does not :D But I guess we want to keep them both to keep the latter as optimized as the current bitmap_{get,set}_value8()?
> > On Fri, Sep 22, 2023 at 10:08:42AM +0200, Alexander Potapenko wrote: >> Currently, when MTE pages are swapped out, the tags are kept in the >> memory, occupying PAGE_SIZE/32 bytes per page. This is especially >> problematic for devices that use zram-backed in-memory swap, because >> tags stored uncompressed in the heap effectively reduce the available >> amount of swap memory. >> >> The RLE-based algorithm suggested by Evgenii Stepanov and implemented in >> this patch series is able to efficiently compress fixed-size tag buffers, >> resulting in practical compression ratio between 2.5x and 4x. In most >> cases it is possible to store the compressed data in 63-bit Xarray values, >> resulting in no extra memory allocations. >> >> Our measurements show that the proposed algorithm provides better >> compression than existing kernel compression algorithms (LZ4, LZO, >> LZ4HC, ZSTD) can offer.
[...]
Thanks, Olek
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