I believe there is performance degradation in NFS4 client:
sudo mount -t nfs4 debmain:/tmp /mnt/tmp
/usr/bin/time -p sh -c 'tree /mnt/tmp | tail -1'
287 directories, 63315 files
real 4.22
user 1.32
sys 1.04
When
/usr/bin/time -p sh -c 'tree /mnt/tmp | tail -1'
is repeated several seconds later the output is this:
287 directories, 63315 files
real 24.64
user 1.58
sys 3.42
I tracked it down to "acregmin" NFS mount option: when "acregmin" is
over/expired directory walk becomes ~5 times slower in my case.
Setting "acregmin=120" on mount will delay the problem for exactly 120
seconds: `tree` will walk directory structure in less than 4 seconds within 2
minutes after first walk, then 120 seconds later it slows down to >24 seconds
needed to walk the same tree again.
Setting "acregmin=0" makes directory walk time >24 seconds even for the first
walk.
Cheers,
Dmitry Smirnov
GPG key : 4096R/53968D1B
--- Package information. ---
Depends (Version) | Installed
=========================================-+-===================
libc6 (>= 2.3) | 2.13-38
libcap2 (>= 2.10) | 1:2.22-1.2
libcomerr2 (>= 1.01) | 1.42.5-1
libdevmapper1.02.1 (>= 2:1.02.20) | 2:1.02.74-6
libevent-2.0-5 (>= 2.0.10-stable) | 2.0.19-stable-3
libgssglue1 | 0.4-2
libk5crypto3 (>= 1.6.dfsg.2) | 1.10.1+dfsg-4
libkeyutils1 | 1.5.5-3
libkrb5-3 (>= 1.6.dfsg.2) | 1.10.1+dfsg-4
libmount1 (>= 2.19.1) | 2.20.1-5.3
libnfsidmap2 | 0.25-4
libtirpc1 | 0.2.2-5
libwrap0 (>= 7.6-4~) | 7.6.q-24
rpcbind | 0.2.0-8
adduser | 3.113+nmu3
ucf | 3.0025+nmu3
lsb-base (>= 1.3-9ubuntu3) | 4.1+Debian8
initscripts (>= 2.88dsf-13.3) | 2.88dsf-41
libblkid1 (>= 2.16) | 2.20.1-5.3
libc6 (>= 2.3) | 2.13-38
libtirpc1 | 0.2.2-5
libwrap0 (>= 7.6-4~) | 7.6.q-24
nfs-common (= 1:1.2.6-3) | 1:1.2.6-3
ucf | 3.0025+nmu3
lsb-base (>= 1.3-9ubuntu3) | 4.1+Debian8
Recommends (Version) | Installed
=========================-+-===========
python | 2.7.3-4
Suggests (Version) | Installed
=========================-+-===========
open-iscsi |
watchdog |