Is your app doing a lot of stat() calls on files it is working with?
This would be a possible source of the getattr calls.
Do you have the noac mount option specified on your NFS clients? If
so, remove it.
By default the nfs client will cache attributes for 30 seconds. This
cache lifetime can be increased if your app doesn't depend on them
(see the mount_nfs man page) and is merely stat'ing a file to see if
it is present, as apps often do.
/dale
On Jun 3, 2009, at 12:04 PM, Mika Borner wrote:
Hi
We are seeing a strange performance problem on some of our NFSv3
clients:
r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device
1.6 0.0 0.6 0.0 37.6 8.8 23506.7 5526.7 100 100 filer:/
vol/mbox4004
0.2 0.0 0.0 0.0 0.0 3.2 0.0 16137.7 0 100 filer:/
vol/mbox4001
3.0 0.2 3.6 0.0 3.7 8.7 1159.9 2718.5 100 100 filer:/
vol/mbox4002
Looking at the mountpoint with fsstat shows:
new name name attr attr lookup rddir read read write write
file remov chng get set ops ops ops bytes ops bytes
46.5M 9.50M 12.8M 6.46G 149K 32.3G 72.3M 91.0M 2.74T 50.9M 246G /
mbox4001
2 0 0 1.64K 0 8.19K 17 2 34 1 17 /
mbox4001
3 0 0 2.92K 0 14.6K 22 1 18 1 17 /
mbox4001
1 0 1 2.90K 0 14.5K 18 23 14.5K 8 60.3K /
mbox4001
What we see is a high number of "attr get" and "lookup ops". Almost
no data is read or written.
I know there is a high cpu load on the NetApp filer, and we are
looking into that problem as well.
I've read somewhere, that NetApp's ONTAP getattr handling is a
single-threaded process. So, my clients might be hammering the
filers to death :-)
Is there any way to lower the lookups a little bit? I know about the
mount options, but I don't want to turn a knob without knowing why...
Thanks for your help!
--
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