44 lines
1.9 KiB
Plaintext
44 lines
1.9 KiB
Plaintext
config ZCACHE
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bool "Dynamic compression of swap pages and clean pagecache pages"
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depends on CRYPTO=y && SWAP=y && CLEANCACHE && FRONTSWAP
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select CRYPTO_LZO
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default n
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help
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Zcache doubles RAM efficiency while providing a significant
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performance boosts on many workloads. Zcache uses
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compression and an in-kernel implementation of transcendent
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memory to store clean page cache pages and swap in RAM,
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providing a noticeable reduction in disk I/O.
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config RAMSTER
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bool "Cross-machine RAM capacity sharing, aka peer-to-peer tmem"
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depends on CONFIGFS_FS=y && SYSFS=y && !HIGHMEM && ZCACHE=y
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depends on NET
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# must ensure struct page is 8-byte aligned
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select HAVE_ALIGNED_STRUCT_PAGE if !64BIT
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default n
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help
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RAMster allows RAM on other machines in a cluster to be utilized
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dynamically and symmetrically instead of swapping to a local swap
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disk, thus improving performance on memory-constrained workloads
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while minimizing total RAM across the cluster. RAMster, like
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zcache2, compresses swap pages into local RAM, but then remotifies
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the compressed pages to another node in the RAMster cluster.
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# Depends on not-yet-upstreamed mm patches to export end_swap_bio_write and
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# __add_to_swap_cache, and implement __swap_writepage (which is swap_writepage
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# without the frontswap call. When these are in-tree, the dependency on
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# BROKEN can be removed
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config ZCACHE_WRITEBACK
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bool "Allow compressed swap pages to be writtenback to swap disk"
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depends on ZCACHE=y && BROKEN
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default n
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help
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Zcache caches compressed swap pages (and other data) in RAM which
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often improves performance by avoiding I/O's due to swapping.
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In some workloads with very long-lived large processes, it can
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instead reduce performance. Writeback decompresses zcache-compressed
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pages (in LRU order) when under memory pressure and writes them to
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the backing swap disk to ameliorate this problem. Policy driving
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writeback is still under development.
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