diff options
Diffstat (limited to 'mm/Kconfig')
| -rw-r--r-- | mm/Kconfig | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/mm/Kconfig b/mm/Kconfig index e9c0c61f2dd..8ca47a5ee9c 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -347,3 +347,26 @@ config NEED_PER_CPU_KM depends on !SMP bool default y + +config CLEANCACHE + bool "Enable cleancache driver to cache clean pages if tmem is present" + default n + help + 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 + cleancacne 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 |