f2fs: combine nat_bits and free_nid_bitmap cache
Both nat_bits cache and free_nid_bitmap cache provide same functionality as a intermediate cache between free nid cache and disk, but with different granularity of indicating free nid range, and different persistence policy. nat_bits cache provides better persistence ability, and free_nid_bitmap provides better granularity. In this patch we combine advantage of both caches, so finally policy of the intermediate cache would be: - init: load free nid status from nat_bits into free_nid_bitmap - lookup: scan free_nid_bitmap before load NAT blocks - update: update free_nid_bitmap in real-time - persistence: udpate and persist nat_bits in checkpoint This patch also resolves performance regression reported by lkp-robot. commit: 4ac91242 ("f2fs: introduce free nid bitmap") d00030cf9cd0bb96fdccc41e33d3c91dcbb672ba ("f2fs: use __set{__clear}_bit_le") 1382c0f3f9d3f936c8bc42ed1591cf7a593ef9f7 ("f2fs: combine nat_bits and free_nid_bitmap cache") 4ac91242 d00030cf9cd0bb96fdccc41e33 1382c0f3f9d3f936c8bc42ed15 ---------------- -------------------------- -------------------------- %stddev %change %stddev %change %stddev \ | \ | \ 77863 ± 0% +2.1% 79485 ± 1% +50.8% 117404 ± 0% aim7.jobs-per-min 231.63 ± 0% -2.0% 227.01 ± 1% -33.6% 153.80 ± 0% aim7.time.elapsed_time 231.63 ± 0% -2.0% 227.01 ± 1% -33.6% 153.80 ± 0% aim7.time.elapsed_time.max 896604 ± 0% -0.8% 889221 ± 3% -20.2% 715260 ± 1% aim7.time.involuntary_context_switches 2394 ± 1% +4.6% 2503 ± 1% +3.7% 2481 ± 2% aim7.time.maximum_resident_set_size 6240 ± 0% -1.5% 6145 ± 1% -14.1% 5360 ± 1% aim7.time.system_time 1111357 ± 3% +1.9% 1132509 ± 2% -6.2% 1041932 ± 2% aim7.time.voluntary_context_switches ... Signed-off-by: NChao Yu <yuchao0@huawei.com> Tested-by: NXiaolong Ye <xiaolong.ye@intel.com> Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>
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