On Mon, Aug 17, 2020 at 03:36:15PM +0800, brookxu wrote: > In the scenario of writing sparse files, the per-inode prealloc list may > be very long, resulting in high overhead for ext4_mb_use_preallocated(). > To circumvent this problem, we limit the maximum length of per-inode > prealloc list to 512 and allow users to modify it. > > After patching, we observed that the sys ratio of cpu has dropped, and > the system throughput has increased significantly. We created a process > to write the sparse file, and the running time of the process on the > fixed kernel was significantly reduced, as follows: > > Running time on unfixed kernel： > [root@TENCENT64 ~]# time taskset 0x01 ./sparse /data1/sparce.dat > real 0m2.051s > user 0m0.008s > sys 0m2.026s > > Running time on fixed kernel： > [root@TENCENT64 ~]# time taskset 0x01 ./sparse /data1/sparce.dat > real 0m0.471s > user 0m0.004s > sys 0m0.395s Thanks, applied with Ritesh's suggested spelling fix up. - Ted
