90 lines
2.5 KiB
Plaintext
90 lines
2.5 KiB
Plaintext
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# SPDX-License-Identifier: GPL-2.0
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config ZRAM
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tristate "Compressed RAM block device support"
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depends on BLOCK && SYSFS && MMU
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depends on CRYPTO_LZO || CRYPTO_ZSTD || CRYPTO_LZ4 || CRYPTO_LZ4HC || CRYPTO_842
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select ZSMALLOC
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help
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Creates virtual block devices called /dev/zramX (X = 0, 1, ...).
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Pages written to these disks are compressed and stored in memory
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itself. These disks allow very fast I/O and compression provides
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good amounts of memory savings.
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It has several use cases, for example: /tmp storage, use as swap
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disks and maybe many more.
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See Documentation/admin-guide/blockdev/zram.rst for more information.
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choice
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prompt "Default zram compressor"
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default ZRAM_DEF_COMP_LZORLE
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depends on ZRAM
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config ZRAM_DEF_COMP_LZORLE
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bool "lzo-rle"
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depends on CRYPTO_LZO
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config ZRAM_DEF_COMP_ZSTD
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bool "zstd"
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depends on CRYPTO_ZSTD
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config ZRAM_DEF_COMP_LZ4
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bool "lz4"
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depends on CRYPTO_LZ4
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config ZRAM_DEF_COMP_LZO
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bool "lzo"
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depends on CRYPTO_LZO
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config ZRAM_DEF_COMP_LZ4HC
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bool "lz4hc"
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depends on CRYPTO_LZ4HC
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config ZRAM_DEF_COMP_842
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bool "842"
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depends on CRYPTO_842
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endchoice
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config ZRAM_DEF_COMP
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string
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default "lzo-rle" if ZRAM_DEF_COMP_LZORLE
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default "zstd" if ZRAM_DEF_COMP_ZSTD
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default "lz4" if ZRAM_DEF_COMP_LZ4
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default "lzo" if ZRAM_DEF_COMP_LZO
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default "lz4hc" if ZRAM_DEF_COMP_LZ4HC
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default "842" if ZRAM_DEF_COMP_842
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config ZRAM_WRITEBACK
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bool "Write back incompressible or idle page to backing device"
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depends on ZRAM
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help
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With incompressible page, there is no memory saving to keep it
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in memory. Instead, write it out to backing device.
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For this feature, admin should set up backing device via
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/sys/block/zramX/backing_dev.
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With /sys/block/zramX/{idle,writeback}, application could ask
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idle page's writeback to the backing device to save in memory.
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See Documentation/admin-guide/blockdev/zram.rst for more information.
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config ZRAM_MEMORY_TRACKING
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bool "Track zRam block status"
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depends on ZRAM && DEBUG_FS
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help
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With this feature, admin can track the state of allocated blocks
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of zRAM. Admin could see the information via
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/sys/kernel/debug/zram/zramX/block_state.
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See Documentation/admin-guide/blockdev/zram.rst for more information.
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config ZRAM_MULTI_COMP
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bool "Enable multiple compression streams"
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depends on ZRAM
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help
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This will enable multi-compression streams, so that ZRAM can
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re-compress pages using a potentially slower but more effective
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compression algorithm. Note, that IDLE page recompression
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requires ZRAM_MEMORY_TRACKING.
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