[LSF/MM TOPIC] Enhancing Copy Tools for Linux FS

[Steve French]

On Fri, Feb 8, 2019 at 4:37 PM Andreas Dilger <adilger at dilger.ca> wrote:
>
> On Feb 8, 2019, at 8:19 AM, Steve French <smfrench at gmail.com> wrote:
> >
> > Current Linux copy tools have various problems compared to other
> > platforms - small I/O sizes (and not even configurable for most),
>
> Hmm, this comment puzzles me, since "cp" already uses s_blksize
> returned for the file as the IO size?  Not sure if tar/rsync do
> the same, but if they don't already use s_blksize they should.

We report a block size of 64K in cifs, but I see cp ignoring that and
issuing 128K (the code in coreutils is a little hard to follow to see
why cp does this), but for long latency networks, larger I/O sizes are
preferred.   cifs.ko would want at least 4MB typically to be passed
down per request since over the wire it negotiates the rsize and wsize
(which typically ends up as 1MB or 4MB) and NFS often uses a 1MB
rsize/wsize over the wire so similar considerations would apply.


-- 
Thanks,

Steve