diff options
Diffstat (limited to 'mm/Kconfig')
| -rw-r--r-- | mm/Kconfig | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/mm/Kconfig b/mm/Kconfig index c2c8a4a11898..b911ad39aa56 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -309,3 +309,25 @@ config NEED_PER_CPU_KM depends on !SMP bool default y + +config CLEANCACHE + bool "Enable cleancache pseudo-RAM driver to cache clean pages" + default y + 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 put + it into a synchronous concurrency-safe page-oriented pseudo-RAM + device (such as Xen's Transcendent Memory, aka "tmem") which 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 pseudo-RAM device is available, 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 |