On Thu, Aug 9, 2018 at 2:08 PM, 刘硕然 <liushuoran@xxxxxx> wrote: > Thanks for the advice. I tried removing BDI_CAP_STRICTLIMIT, and it works. There is no balance_dirty_pages() triggered, and the performance improves a lot. > > Tested by libfuse passthrough_ll example and fio: > ./passthrough_ll -o writeback /mnt/fuse/ > fio --name=test --ioengine=psync --directory=/mnt/fuse/home/test --bs=4k --direct=0 --size=64M --rw=write --fallocate=0 --numjobs=1 > > performance with BDI_CAP_STRICTLIMIT: > WRITE: bw=158MiB/s (165MB/s), 158MiB/s-158MiB/s (165MB/s-165MB/s), io=64.0MiB (67.1MB), run=406-406msec > > Performance without BDI_CAP_STRICTLIMIT: > WRITE: bw=1561MiB/s (1637MB/s), 1561MiB/s-1561MiB/s (1637MB/s-1637MB/s), io=64.0MiB (67.1MB), run=41-41msec > > However, I wonder if there are some side-effects to remove it? Since it seems that the original purpose of this feature is to prevent FUSE from consuming too much memory. Yes. So if BDI_CAP_STRICTLIMIT is causing a serious performance bottleneck, then we need to think about solving this without losing the benefits. Simply removing it is definitely not a proper solution. Thanks, Miklos
