caching issue with nocto

caching issue with nocto

[Bjørnar Ness]

Mounting with nocto option drasticly improves performance, but doing
some tests, it seems that if a file is modified, either from the
client doing the mount or other client, the file is never cached
again.

Can this be seen as a bug?

Test:

while true;do time cat /usr/src/linux-3.9.5(include/linux/*.h >/dev/null;done

Stabilizes on ~10ms here with nocto

But then, if touching a file from either same client or other, time
skyrockets, and never gets back to anything near 10ms! Only solution
is to unmount and mount again..


Is this expected behaviour?

--
Bj(/)rnar

Re: caching issue with nocto

[Bjørnar Ness]

I have not yet received any feedback on this issue. Can someone please take
a look into this?

Seems like updating mtime on the folder from different client is causes nocto to
stop working on a mount (or a subfolder of the mount)

client1:

mount -t nfs -o
vers=3,noatime,nodiratime,noacl,ac,sharecache,lookupcache=all,nocto
10.30.0.11/foo /mnt
while true; do time cat /mnt/linux-headers/*.h >/dev/null ; done

real 0m1.037s
user 0m0.008s
sys 0m0.088s

real 0m0.021s
user 0m0.008s
sys 0m0.008s

[...]

client2:

same mount,

touch /mnt/linux-headers


What happends (after few secs) is client1 times goes to over a sec and
stays there for infinity.

a -o remount (run a few times) solves problem (until client2 touches a
folder again..)

--
Bj(/)rnar