This patchset introduces a new memory allocator for persistent pages for zcache. The current allocator is xvmalloc. xvmalloc has two notable limitations: * High (up to 50%) external fragmentation on allocation sets > PAGE_SIZE/2 * No compaction support which reduces page reclaimation xcfmalloc seeks to fix these issues by using scatter-gather model that allows for cross-page allocations and relocatable data blocks. In tests, with pages that only compress to 75% of their original size, xvmalloc had an effective compression (pages stored / pages used by the compressed memory pool) of ~95% (~20% lost to fragmentation). Almost nothing was gained by the compression in this case. xcfmalloc had an effective compression of ~77% (about ~2% lost to fragmentation and metadata overhead). xcfmalloc uses the same locking scheme as xvmalloc; a single pool-level spinlock. This can lead to some contention. However, in my tests on a 4 way SMP system, the contention was minimal (200 contentions out of 600k aquisitions). The locking scheme may be able to be improved in the future. In tests, xcfmalloc and xvmalloc had identical throughputs. While the xcfmalloc design lends itself to compaction, this is not yet implemented. Support will be added in a follow-on patch. Based on 3.1-rc4. Seth Jennings (3): staging: zcache: xcfmalloc memory allocator for zcache staging: zcache: replace xvmalloc with xcfmalloc staging: zcache: add zv_page_count and zv_desc_count drivers/staging/zcache/Makefile | 2 +- drivers/staging/zcache/xcfmalloc.c | 653 ++++++++++++++++++++++++++++++++++ drivers/staging/zcache/xcfmalloc.h | 29 ++ drivers/staging/zcache/zcache-main.c | 154 ++++++--- 4 files changed, 791 insertions(+), 47 deletions(-) create mode 100644 drivers/staging/zcache/xcfmalloc.c create mode 100644 drivers/staging/zcache/xcfmalloc.h -- 1.7.4.1 _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
