On 2019/8/26 20:39, Miklos Szeredi wrote:
On Sat, Aug 24, 2019 at 10:44 AM wangyan <wangyan122@xxxxxxxxxx> wrote:
According to the result, for "-size=1G", it maybe exceed the dirty pages'
upper limit, and it frequently triggered pdflush for write-back. And for
"-size=700M", it maybe didn't exceed the dirty pages' upper limit, so no
extra pdflush was triggered.
But for 9p using "-size=1G", the latency 3.94 usec, and the bandwidth is
2305.5MB/s. It is better than virtiofs using "-size=1G". It seems that
it is not affected by the dirty pages' upper limit.
I tried to reproduce these results, but failed to get decent
(>100MB/s) performance out of 9p. I don't have fscache set up, does
that play a part in getting high performance cached writes?
Yes, you should open fscache. My mount command is:
mount -t 9p -o
trans=virtio,version=9p2000.L,rw,dirsync,nodev,msize=1000000000,cache=fscache
sharedir /mnt/virtiofs/
Thanks,
Yan Wang
What you describe makes sense, and I have a new patch (attached), but
didn't see drastic improvement in performance of virtio-fs in my
tests.
Thanks,
Miklos
