samba 3.0.20 vs. 3.0.14a dbench failure

Jeremy Allison jra at
Sun Aug 21 23:38:36 GMT 2005

On Sun, Aug 21, 2005 at 06:19:52PM -0500, Steve French wrote:
> I am seeing a possible problem with Samba 3.0.20 under stress.
> Running dbench (70 processes, current Linux icifs mounted against smbd 
> on localhost) against Samba 3.0.20 smbd failed with a few read failures 
> (I did not catch debug information to see what the failures were), and 
> also what appear to be unexpected sharing violations during the cleanup 
> phase.   This works on the same system when running smbd from Samba 
> 3.0.14a (instead of 3.0.20).    I also tried with smbfs which seemed to 
> have problems during the cleanup phase.   I also did see one run against 
> 3.0.20 in which a command timed out (ReadX I think) which would indicate 
> a response taking longer than 15 seconds, which I had not seen against 
> 3.0.14a.
> This is not enough information to point to the exact failure, but taking 
> snapshots of the mid queue from time to time randomly on the client side 
> (with cifs vfs mounted to 3.0.20) show various inflight requests which 
> already had taken longer than 2 seconds, and some even taking longer 
> than 4 seconds which is far longer than I would expect.  These slow 
> responses seem to come in bursts with more than one slow response 
> perhaps holding up others. The requests that I have logged taking more 
> than 4 seconds to Samba 3.0.20 are ReadX (typically for 16k) size), 
> OpenX, and Transact2 (do not know which subcommand).    These tests were 
> run against localhost on a 1.2Ghz Pentium 3 system which should be able 
> to handle 70 processes for dbench (and has done fine with Samba 3.0.14a).

I'm assuming this is with 3.0.14a on exactly the same system. If so,
try setting debug level 10 and split out the logs as much as possible.
It will increase the load and show the problem at lower levels, but it
should do the same for both 3.0.14a and 3.0.20 - it'll give us more
info on what the problem may be.


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