Differences between 2.6.5 und 2.6.16: getattr with actimeo=0 and O_DIRECT

[Gerd Bavendiek <gerd.bavendiek@googlemail.com>]

Hi,

analyzing performance issues with Oracle databases on an NFS client
running on SLES9 SP3 and NetApp as NFS server, I found that in SLES9
SP3 each write call is followed by an getattr. This is not the case
with SLES10 SP1.

Mount options in use are:

rw,v3,rsize=32768,wsize=32768,acregmin=0,acregmax=0,acdirmin=0,acdirmax=0,hard,lock,proto=tcp,addr=172.18.131.134

I do

dd if=/dev/zero of=/mnt/qqq oflag=direct bs=8k count=100000

and using tcpdump (BTW, is there an easier way ?) I see with SLES9 SP3
(i.e. 2.6.5-7.244) each single 8k write followed by an getattr (which
comes at some cost).

Using SLES10 SP1 (2.6.16.46-0.12) there is only one getattr when dd
closes the file.

Is there anything I can do to avoid the getattr calls in SLES9 SP3
(no, sorry, can't update to SLES10 SP1) ?

Thanks

Gerd


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