CONFIG_CLEANCACHE: Enable cleancache driver to cache clean pages if tmem is present

General informations

The Linux kernel configuration item CONFIG_CLEANCACHE:

• prompt: Enable cleancache driver to cache clean pages if tmem is present
• type: bool
• depends on: (none)
• defined in mm/Kconfig
• found in Linux kernels: 3.0–3.19, 4.0–4.20, 5.0–5.16, 5.16+HEAD

Help text

Cleancache can be thought of as a page-granularity victim cache for clean pages that the kernel's pageframe replacement algorithm (PFRA) would like to keep around, but can't since there isn't enough memory. So when the PFRA "evicts" a page, it first attempts to use cleancache code to put the data contained in that page into "transcendent memory", memory that is not directly accessible or addressable by the kernel and is of unknown and possibly time-varying size. And when a cleancache-enabled filesystem wishes to access a page in a file on disk, it first checks cleancache to see if it already contains it; if it does, the page is copied into the kernel and a disk access is avoided. When a transcendent memory driver is available (such as zcache or Xen transcendent memory), a significant I/O reduction may be achieved. When none is available, all cleancache calls are reduced to a single pointer-compare-against-NULL resulting in a negligible performance hit.

If unsure, say Y to enable cleancache

Hardware

LKDDb

Raw data from LKDDb:

• (none)

Sources

This page is automaticly generated with free (libre, open) software lkddb(see lkddb-sources).

The data is retrived from:

• Linux kernel
• Linux Kernel Driver DataBase (LKDDb)

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