• Coly Li's avatar
    bcache: add readahead cache policy options via sysfs interface · 038ba8cc
    Coly Li authored
    In year 2007 high performance SSD was still expensive, in order to
    save more space for real workload or meta data, the readahead I/Os
    for non-meta data was bypassed and not cached on SSD.
    
    In now days, SSD price drops a lot and people can find larger size
    SSD with more comfortable price. It is unncessary to alway bypass
    normal readahead I/Os to save SSD space for now.
    
    This patch adds options for readahead data cache policies via sysfs
    file /sys/block/bcache<N>/readahead_cache_policy, the options are,
    - "all": cache all readahead data I/Os.
    - "meta-only": only cache meta data, and bypass other regular I/Os.
    
    If users want to make bcache continue to only cache readahead request
    for metadata and bypass regular data readahead, please set "meta-only"
    to this sysfs file. By default, bcache will back to cache all read-
    ahead requests now.
    
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarColy Li <colyli@suse.de>
    Acked-by: default avatarEric Wheeler <bcache@linux.ewheeler.net>
    Cc: Michael Lyle <mlyle@lyle.org>
    Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
    038ba8cc
bcache.h 31.9 KB