From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Alexander Potapenko <glider@google.com>,
Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: catalin.marinas@arm.com, will@kernel.org, pcc@google.com,
andreyknvl@gmail.com, linux@rasmusvillemoes.dk,
yury.norov@gmail.com, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, eugenis@google.com,
syednwaris@gmail.com, william.gray@linaro.org
Subject: Re: [PATCH v5 0/5] Implement MTE tag compression for swapped pages
Date: Fri, 22 Sep 2023 17:35:19 +0300 [thread overview]
Message-ID: <ZQ2mJ9rK7xNoMykL@smile.fi.intel.com> (raw)
In-Reply-To: <20230922080848.1261487-1-glider@google.com>
+Cc: Olek, who internally is being developed something similar to your first
patch here.
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.
>
> To implement compression/decompression, we also extend <linux/bitmap.h>
> with methods to read/write bit values at arbitrary places in the map.
>
> We refactor arch/arm64/mm/mteswap.c to support both the compressed
> (CONFIG_ARM64_MTE_COMP) and non-compressed case. For the former, in
> addition to tag compression, we move tag allocation from kmalloc() to
> separate kmem caches, providing greater locality and relaxing the
> alignment requirements.
>
> v5:
> - fixed comments by Andy Shevchenko, Catalin Marinas, and Yury Norov
> - added support for 16K- and 64K pages
> - more efficient bitmap_write() implementation
>
> v4:
> - fixed a bunch of comments by Andy Shevchenko and Yury Norov
> - added Documentation/arch/arm64/mte-tag-compression.rst
>
> v3:
> - as suggested by Andy Shevchenko, use
> bitmap_get_value()/bitmap_set_value() written by Syed Nayyar Waris
> - switched to unsigned long to reduce typecasts
> - simplified the compression code
>
> v2:
> - as suggested by Yuri Norov, replace the poorly implemented struct
> bitq with <linux/bitmap.h>
>
>
>
> Alexander Potapenko (4):
> lib/test_bitmap: add tests for bitmap_{read,write}()
> arm64: mte: implement CONFIG_ARM64_MTE_COMP
> arm64: mte: add a test for MTE tags compression
> arm64: mte: add compression support to mteswap.c
>
> Syed Nayyar Waris (1):
> lib/bitmap: add bitmap_{read,write}()
>
> Documentation/arch/arm64/index.rst | 1 +
> .../arch/arm64/mte-tag-compression.rst | 245 +++++++++
> arch/arm64/Kconfig | 21 +
> arch/arm64/include/asm/mtecomp.h | 13 +
> arch/arm64/mm/Makefile | 7 +
> arch/arm64/mm/mtecomp.c | 467 ++++++++++++++++++
> arch/arm64/mm/mtecomp.h | 12 +
> arch/arm64/mm/mteswap.c | 20 +-
> arch/arm64/mm/mteswap.h | 12 +
> arch/arm64/mm/mteswap_comp.c | 60 +++
> arch/arm64/mm/mteswap_nocomp.c | 38 ++
> arch/arm64/mm/test_mtecomp.c | 287 +++++++++++
> include/linux/bitmap.h | 68 +++
> lib/test_bitmap.c | 115 +++++
> 14 files changed, 1355 insertions(+), 11 deletions(-)
> create mode 100644 Documentation/arch/arm64/mte-tag-compression.rst
> create mode 100644 arch/arm64/include/asm/mtecomp.h
> create mode 100644 arch/arm64/mm/mtecomp.c
> create mode 100644 arch/arm64/mm/mtecomp.h
> create mode 100644 arch/arm64/mm/mteswap.h
> create mode 100644 arch/arm64/mm/mteswap_comp.c
> create mode 100644 arch/arm64/mm/mteswap_nocomp.c
> create mode 100644 arch/arm64/mm/test_mtecomp.c
>
> --
> 2.42.0.515.g380fc7ccd1-goog
>
--
With Best Regards,
Andy Shevchenko
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-09-22 14:36 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-22 8:08 [PATCH v5 0/5] Implement MTE tag compression for swapped pages Alexander Potapenko
2023-09-22 8:08 ` [PATCH v5 1/5] lib/bitmap: add bitmap_{read,write}() Alexander Potapenko
2023-09-22 8:08 ` [PATCH v5 2/5] lib/test_bitmap: add tests for bitmap_{read,write}() Alexander Potapenko
2023-09-25 12:16 ` Alexander Potapenko
2023-09-25 12:23 ` Andy Shevchenko
2023-09-25 13:09 ` Alexander Potapenko
2023-09-25 14:54 ` Alexander Potapenko
2023-09-25 16:06 ` Yury Norov
2023-09-25 17:16 ` Alexander Potapenko
2023-09-27 7:51 ` David Laight
2023-09-28 14:19 ` Alexander Potapenko
[not found] ` <CAAH8bW-9ZWB=i0RWAWBXguOkguLHZGp7fLg7An73NqFnVmtgFw@mail.gmail.com>
2023-09-28 15:14 ` Alexander Potapenko
2023-09-28 19:59 ` Yury Norov
2023-09-29 8:54 ` Alexander Potapenko
2023-10-02 2:44 ` Yury Norov
2023-10-02 7:34 ` Alexander Potapenko
2023-09-22 8:08 ` [PATCH v5 3/5] arm64: mte: implement CONFIG_ARM64_MTE_COMP Alexander Potapenko
2023-09-22 8:08 ` [PATCH v5 4/5] arm64: mte: add a test for MTE tags compression Alexander Potapenko
2023-09-22 8:08 ` [PATCH v5 5/5] arm64: mte: add compression support to mteswap.c Alexander Potapenko
2023-09-22 14:35 ` Andy Shevchenko [this message]
2023-09-22 14:40 ` [PATCH v5 0/5] Implement MTE tag compression for swapped pages Alexander Lobakin
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