Sorry for trouble again. I just wrote wrong function name in previous sending, so resend it. If you have received previous email please ignore it, thanks we have a XFS mkfs with "-k" and mount with the default options( rw,relatime,attr2,inode64,noquota), the size is about 2.2TB,and exported via samba. [root@test1 home]# xfs_info /dev/sdk meta-data=/dev/sdk isize=512 agcount=4, agsize=131072000 blks = sectsz=4096 attr=2, projid32bit=1 = crc=1 finobt=0 spinodes=0 data = bsize=4096 blocks=524288000, imaxpct=5 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 ftype=1 log =internal bsize=4096 blocks=256000, version=2 = sectsz=4096 sunit=1 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0 free space about allocation groups: from to extents blocks pct 1 1 9 9 0.00 2 3 14291 29124 0.19 4 7 5689 22981 0.15 8 15 119 1422 0.01 16 31 754657 15093035 99.65 32 63 1 33 0.00 total free extents 774766 total free blocks 15146604 average free extent size 19.5499 from to extents blocks pct 1 1 253 253 0.00 2 3 7706 16266 0.21 4 7 7718 30882 0.39 8 15 24 296 0.00 16 31 381976 7638130 96.71 32 63 753 38744 0.49 131072 262143 1 173552 2.20 total free extents 398431 total free blocks 7898123 average free extent size 19.8231 from to extents blocks pct 1 1 370 370 0.00 2 3 2704 5775 0.01 4 7 1016 4070 0.01 8 15 24 254 0.00 16 31 546614 10931743 20.26 32 63 19191 1112600 2.06 64 127 2 184 0.00 131072 262143 1 163713 0.30 524288 1048575 2 1438626 2.67 1048576 2097151 4 5654463 10.48 2097152 4194303 1 3489060 6.47 4194304 8388607 2 12656637 23.46 16777216 33554431 1 18502975 34.29 total free extents 569932 total free blocks 53960470 average free extent size 94.6788 from to extents blocks pct 1 1 8 8 0.00 2 3 5566 11229 0.06 4 7 9622 38537 0.21 8 15 57 686 0.00 16 31 747242 14944852 80.31 32 63 570 32236 0.17 2097152 4194303 1 3582074 19.25 total free extents 763066 total free blocks 18609622 average free extent size 24.38 we copy small files(about 150kb) from windows to xfs via SMB protocal, sometines kworker process consumes 100% of one CPU, and "perf top" shows xfs_extent_busy_trim() and xfs_btree_increment() consume too much cpu resources, ftrace also show xfs_alloc_ag_vextent_near takes about 30ms to complete. In addition all tests were performed on Centos7.4(3.10.0-693.el7.x86_64). Any suggestions are welcome.