linux-kernel - Re: Massive slowdown when re-querying large nfs dir

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Date:	Tue, 6 Nov 2007 14:28:11 +0300
From:	Al Boldi <a1426z@...ab.com>
To:	linux-fsdevel@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Massive slowdown when re-querying large nfs dir

Al Boldi wrote:
> There is a massive (3-18x) slowdown when re-querying a large nfs dir (2k+
> entries) using a simple ls -l.
>
> On 2.6.23 client and server running userland rpc.nfs.V2:
> first  try: time -p ls -l <2k+ entry dir>  in ~2.5sec
> more tries: time -p ls -l <2k+ entry dir>  in ~8sec
>
> first  try: time -p ls -l <5k+ entry dir>  in ~9sec
> more tries: time -p ls -l <5k+ entry dir>  in ~180sec
>
> On 2.6.23 client and 2.4.31 server running userland rpc.nfs.V2:
> first  try: time -p ls -l <2k+ entry dir>  in ~2.5sec
> more tries: time -p ls -l <2k+ entry dir>  in ~7sec
>
> first  try: time -p ls -l <5k+ entry dir>  in ~8sec
> more tries: time -p ls -l <5k+ entry dir>  in ~43sec
>
> Remounting the nfs-dir on the client resets the problem.
>
> Any ideas?

Ok, I played some more with this, and it turns out that nfsV3 is a lot 
faster.  But, this does not explain why the 2.4.31 kernel is still over 
4-times faster than 2.6.23.

Can anybody explain what's going on?


Thanks!

--
Al

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