client: 2.6.7 client much slower than 2.4.26

client: 2.6.7 client much slower than 2.4.26

[Bernd Schubert]

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Hi,

I'm currently testing 2.6.7 on one of our clients and the nfs transfer is much 
slower than when the same system is running 2.4.X

Well, the usual suggestion probably would be to run nfs over tcp now, but tcp 
is already enabled (from /proc/mounts):

taylor:/worka /mnt/test nfs 
rw,v3,rsize=32768,wsize=32768,hard,tcp,lock,addr=taylor 0 0

benchmarks:

copy a file to the server (2.6.7): ~ 3MB/s
copy a file to the server (2.4.26): ~ 9MB/s

copy a file from the server (2.6.7): ~ 3MB/s
copy a file from the server (2.4.26): ~ 11MB/s

The filesize was 300MB.


Here's the nfsstat output:

euklid:~# nfsstat
Client rpc stats:
calls      retrans    authrefrsh
385466     0          0
Client nfs v2:
null       getattr    setattr    root       lookup     readlink
0       0% 27475  66% 231     0% 0       0% 3963    9% 161     0%
read       wrcache    write      create     remove     rename
8303   20% 0       0% 560     1% 171     0% 198     0% 42      0%
link       symlink    mkdir      rmdir      readdir    fsstat
45      0% 0       0% 3       0% 3       0% 129     0% 2       0%

Client nfs v3:
null       getattr    setattr    lookup     access     readlink
0       0% 56851  16% 1047    0% 17711   5% 36670  10% 936     0%
read       write      create     mkdir      symlink    mknod
73640  21% 149802 43% 629     0% 86      0% 1       0% 0       0%
remove     rmdir      rename     link       readdir    readdirplus
701     0% 105     0% 279     0% 36      0% 464     0% 1557    0%
fsstat     fsinfo     pathconf   commit
260     0% 18      0% 0       0% 3387    0%


I already tried to reduce rsize and wsize up to 1024, but this didn't change 
anything.

This happens to two different servers, one server is running 2.6.7 and has 
Gigabit connection to the switch. The other server is running 2.4.25 and only 
has a 100MBit connection. All of our clients have 100MBit connections.

So I really thing this is a client problem. Well, the client is not the 
fastest of our systems (PII 450), but with 2.4.X it has the usual speed. Its 
also interesting top is showing that the rpciod is taking all cpu-time when 
copying a file to the server.

Any ideas whats going on?

Thanks,
	Bernd

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Re: client: 2.6.7 client much slower than 2.4.26

[Trond Myklebust]

P=E5 to , 01/07/2004 klokka 17:18, skreiv Bernd Schubert:

> benchmarks:
>=20
> copy a file to the server (2.6.7): ~ 3MB/s
> copy a file to the server (2.4.26): ~ 9MB/s
>=20
> copy a file from the server (2.6.7): ~ 3MB/s
> copy a file from the server (2.4.26): ~ 11MB/s

Looks like the wire speeds on read/write are the same. How does the
above compare to ttcp transfer speeds of a 300MB file?


> Here's the nfsstat output:

What's that for, 2.4.26 or 2.6.7? How does it compare?

> So I really thing this is a client problem. Well, the client is not the=20
> fastest of our systems (PII 450), but with 2.4.X it has the usual speed. =
Its=20
> also interesting top is showing that the rpciod is taking all cpu-time wh=
en=20
> copying a file to the server.

How much memory does this thing have? The main difference between 2.4.x
and 2.6.x is the fact that the 2.6.x caches a lot more data and for
longer (the VM is what decides when to flush the cache).
You might want to try twiddling around with the vm sysctl parameters to
see if that makes a difference.

Cheers,
  Trond


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Re: client: 2.6.7 client much slower than 2.4.26

[Bernd Schubert]

On Thursday 01 July 2004 23:43, you wrote:
> P=E5 to , 01/07/2004 klokka 17:18, skreiv Bernd Schubert:
> > benchmarks:
> >
> > copy a file to the server (2.6.7): ~ 3MB/s
> > copy a file to the server (2.4.26): ~ 9MB/s
> >
> > copy a file from the server (2.6.7): ~ 3MB/s
> > copy a file from the server (2.4.26): ~ 11MB/s
>
> Looks like the wire speeds on read/write are the same. How does the
> above compare to ttcp transfer speeds of a 300MB file?

Thanks, I didn't know about this tool and I think you are right, it seems t=
hat=20
the general network speed is much slower with 2.6.7:

2.4.26:
bernd@euklid bernd>nttcp -T taylor
     Bytes  Real s   CPU s Real-MBit/s  CPU-MBit/s   Calls  Real-C/s   CPU-=
C/s
l  8388608    0.70    0.06     95.2480   1118.4811    2048   2906.74   3413=
3.3
1  8388608    0.71    0.03     94.1283   2485.7897    5793   8125.38  21457=
9.4

2.6.7:
bernd@euklid bernd>nttcp -T taylor
     Bytes  Real s   CPU s Real-MBit/s  CPU-MBit/s   Calls  Real-C/s   CPU-=
C/s
l  8388608    2.67    2.64     25.1472     25.4046    2048    767.43     77=
5.3
1  8388608    2.67    0.03     25.1442   2237.3350    6145   2302.40  20486=
7.5

Its already too late, so I will do the 300MB test tomorrow, but I think the=
=20
numbers from the default 8MB test are already convincing.


> How much memory does this thing have? The main difference between 2.4.x

Somehow this system didn't like to have more than 2x128MB, when we added=20
another DIMM, the system crashed pretty often, though memtest86 showed no=20
problems.=20

> and 2.6.x is the fact that the 2.6.x caches a lot more data and for
> longer (the VM is what decides when to flush the cache).
> You might want to try twiddling around with the vm sysctl parameters to
> see if that makes a difference.
>

I will try to play with this over the weekend.


Thanks again a lot for your help!


Cheers,
	Bernd


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