On Thu, Dec 26, 2019 at 05:13:59PM -0600, Bruce Dubbs via blfs-support wrote:
> On 12/26/19 3:30 PM, Ken Moffat via blfs-support wrote:
> 
> For comparison:
> 
> "server": Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz  (Skylake)  8M Ram
> "client: Intel(R) Core(TM) i7-5820K CPU @ 3.30GHz (Haswell) 16M Ram
> 
> The "server" is lfs84:
> bdubbs@lfs84 [ /usr/src/firefox ]$ time tar -xf
> firefox-68.3.0esr.source.tar.xz
> 
> real    0m27.463s
> user    0m20.244s
> sys     0m4.764s
> 
> The "client" is frodo90:
> 
> $ findmnt /usr/src
> TARGET   SOURCE         FSTYPE OPTIONS
> /usr/src lfs84:/srv/src nfs
> rw,noatime,vers=3,rsize=1048576,wsize=1048576,namlen=255,hard,prot
> 
> bdubbs@frodo90 [ /build ]$ time tar -xf
> /usr/src/firefox/firefox-68.3.0esr.source.tar.xz
> 
> real    0m26.324s
> user    0m17.304s
> sys     0m5.454s
> 
> But if I do:
> bdubbs@frodo90 [ /build ]$ cd /usr/src/firefox
> bdubbs@frodo90 [ /usr/src/firefox ]$ time tar -xf
> /usr/src/firefox/firefox-68.3.0esr.source.tar.xz
> 
> Abort after an hour.  The tarball expands to 2.6G, but I terminated at 256M.
> My conclusion is that reads over nfs are reasonably fast, but writes are
> extremely slow.
> 
>   -- Bruce
> 
I can see similar slowness when I try to untar in my nfs export, but
for the first stage of my backups I use rsync to an nfs mount -
obviously the first _system_ backup is slow, but general updates
after that (only changed/added files are not too bad.  And writes to
my notes (and downloading tarballs to my sources) are all over nfs
and seem fine.

But for this specific slowness, please see
https://bugzilla.redhat.com/show_bug.cgi?id=790232
specifically the first part of comment 2 - the sync to disk for each
created file is presumably the reason for the slowness.

So, don't build big source packages in an nfs mount (similar
slowness will presumably happen on each created file during a
compile).

ĸen
-- 
          We've all got both light and dark inside of us.
          What matters is the part we choose to act on.
                                              -- Sirius Black
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