Performance issue with Vista

Hi,

I tested a little bit Samba with Windows vista and found
serious performance issue regarding reading large files from
Samba server. Computers that I tested Samba with were all
identical computers equipped with 2,8 GHz Pentium D
processors, 1 GB memory and 1 Gbit/s LAN. All computers have
only external USB hard drives so that it is easier to change
from operating system to another.

First I tested performance with 160 MB tar.gz file and there
were no problems. SMBClient from another Linux computer
reads and writes about 45 MB/s. Performance on Vista Client
was higher than this. Write was just a little bit under 50
MB/s and read 48 MB/s. Then I moved to larger files to make
sure that I would get results that simulate better the
environment, where I need Samba myself (Saving and reading
500-1000 MB images from and to Photoshop)
. I chose 690MB Knoppix image. Read and write from SMBclient
were 27 to 28 MB/s at average. Writing from Vista bursts at
50 MB/s and minimum was 28 MB/s leading to over 30 MB/s
average. _Then to the problem_: Reading from Samba share
gave bursts of 6 MB/s and repeated drops to 0,5 MB/s.

I have same kind of problem also at home (at the moment 100
MB/s network) using same version of samba and nearly
identical configuration file. SMBClient reads and writes ok
but performance from Windows XP is poor (but in this case
both reading and writing)

Has anyone else encountered same behaviour and is there any
workarounds for this. Linux systems that I use are Debian
Sarge 3.1r5 and Samba version is 3.0.14a-3s.

Thanks in advance,
Mikko Pukki

smb.conf global settings:

[global]
   workgroup = *********
   server string = %h server (Samba %v)
   dns proxy = no
   log file = /var/log/samba/log.%m
   max log size = 1000
   syslog = 0
   panic action = /usr/share/samba/panic-action %d
   encrypt passwords = true  
   passdb backend = tdbsam guest
   obey pam restrictions = yes
   invalid users = root
   passwd program = /usr/bin/passwd %u
   passwd chat = *EntersnewsUNIXspassword %nn
*RetypesnewsUNIXspassword %nn .

         SO_RCVBUF=8192 SO_SNDBUF=8192
   socket options = TCP_NODELAY

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>Hi,
>these problems have been discussed many times in the
last weeks.
>Solution: get rid of SO_RCVBUF=8192 and SO_SNDBUF=8192
and your speed 
>will increase.
>modern kernels do a much better job in handling these
buffersizes than 
>you can.
>Christoph

And because of those discussions I tried also without
changing buffers and I also tried to change them to 16384 (I
noticed that in first mail I sent modifiers are on the wrong
line but they are correct in actual smb.conf). When at 8192
or 16384 it gave once a burst of 500 Mbit/s but it lasted
only for half a second. Maybe something from previous
transfer was buffered somewhere (I'm not an expert on CIFS
and Vista is quite new for me). After that peak tansfer
drops to ~5Mbit/s and rises to 60 Mbit/s and drops again.
Average might be close to 40 Mbit/s. Those 60 Mbit peaks
seem quite flat topped in task manager. It does this no
matter what buffer sizes I have tried. With last
configuration I was able to read 25MB/s from smbclient.

If I recall correctly, I got best transfer speeds with
smbclient when socket options were default. No matter what
the settings are, writing from Vista to Samba is always
faster than from another Linux machine using smbclient. I
also tried NFS and SCP transfers and they lagged big time
behind Samba. Kernel in Linux is 2.6.8-3 if that makes any
difference. Would upgrading Samba help? There would only be
one problem in updating from 3.0.14a-3s.. All the systems
should use Sarge and that is newest version available.

Mikko
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On Thu, Feb 22, 2007 at 03:44:56PM +0200, Mikko Pukki
wrote:
> Hi,
> 
> I tested a little bit Samba with Windows vista and
found serious performance issue regarding reading large
files from Samba server. Computers that I tested Samba with
were all identical computers equipped with 2,8 GHz Pentium D
processors, 1 GB memory and 1 Gbit/s LAN. All computers have
only external USB hard drives so that it is easier to change
from operating system to another.
> 
> First I tested performance with 160 MB tar.gz file and
there were no problems. SMBClient from another Linux
computer reads and writes about 45 MB/s. Performance on
Vista Client was higher than this. Write was just a little
bit under 50 MB/s and read 48 MB/s. Then I moved to larger
files to make sure that I would get results that simulate
better the environment, where I need Samba myself (Saving
and reading 500-1000 MB images from and to Photoshop)
> . I chose 690MB Knoppix image. Read and write from
SMBclient were 27 to 28 MB/s at average. Writing from Vista
bursts at 50 MB/s and minimum was 28 MB/s leading to over 30
MB/s average. _Then to the problem_: Reading from Samba
share gave bursts of 6 MB/s and repeated drops to 0,5 MB/s.
> 
> I have same kind of problem also at home (at the moment
100 MB/s network) using same version of samba and nearly
identical configuration file. SMBClient reads and writes ok
but performance from Windows XP is poor (but in this case
both reading and writing)
> 
> Has anyone else encountered same behaviour and is there
any workarounds for this. Linux systems that I use are
Debian Sarge 3.1r5 and Samba version is 3.0.14a-3s.

We've done some work on this for 3.0.25 - check out the new
vfs_readahead module.

Jeremy.
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