[pve-devel] [RFC PATCH pve-cluster] fix #5728: pmxcfs: allow bigger writes than 4k for fuse

[Dietmar Maurer]

> > [...] 
> > so a factor of 32 less calls to cfs_fuse_write (including memdb_pwrite)
> 
> That can be huge or not so big at all, i.e. as mentioned above, it would we good to
> measure the impact through some other metrics.
> 
> And FWIW, I used bpftrace to count [0] with an unpatched pmxcfs, there I get
> the 32 calls to cfs_fuse_write only for a new file, overwriting the existing
> file again with the same amount of data (128k) just causes a single call.
> I tried using more data (e.g. from 128k initially to 256k or 512k) and it's
> always the data divided by 128k (even if the first file has a different size)

I observe the same thing. Seems the fuse2 use 4K block for new files, but 128K if the file already exists...