[PVFS-developers] Re: [PVFS-users] Recompile pvfs module for SuSE 2.4.19-NUMA

[Claude Pignol]

Thanks Rob,

Another fact:
I found that the read works very well with 64K I/O: the read speed is 
better than the write speed.
The read perf start degrading when I increase the I/O size

I agree that there is a starting cost but there is the read ahead mechanism
that speed up the disk access.
I am testing with file of min 1GB

I have tested with dynamic buffering (the default) and the static buffering.
Same problem.
How do you increase tcp buffer size?
net.ipv4.tcp_rmem
net.ipv4.tcp_wmem
net.ipv4.tcp_mem


Claude


Rob Ross wrote:

>Hi Claude,
>
>Sorry we didn't get back to you sooner.  I'm glad that the kernel update 
>fixed the problem.
>
>What block size (bs=XXX) are you using in your tests?
>
>Note that when reading no I/O can start until data is read off disk, while 
>in the write case data can start moving right away.  So you may just be 
>seeing startup costs.
>
>You could look at increasing TCP buffer sizes on your system as a first 
>step.
>
>Regards,
>
>Rob
>
>On Mon, 8 Mar 2004, Claude Pignol wrote:
>
>  
>
>>Greetings,
>>
>>An upgrade to 2.4.21 fixes the problem.
>>Compile and start OK.
>>I have noticed a performance problem in reading from PVFS.
>>With big I/O (few MB) reading is around 1/3 of the performance of writing.
>>Pvfs deamons with default parameters
>>Reading/Writing from on node to pvfs using dd.
>>I have verified the disk performance of all the 10 I/O nodes
>>I have also verified the network perf to all the nodes.
>>What is the best strategy/tools to address this kind of problem?
>>Thanks
>>
>>
>>Claude Pignol wrote:
>>
>>    
>>
>>>Greetings,
>>>
>>>I try to do a benchmark of pvfs with the SuSE 2.4.19-NUMA kernel
>>>to compare with the SuSE 2.4.19-SMP kernel.
>>>No problem to compile and load the pvfs.o module with the SMP kernel
>>>
>>>With the NUMA kernel I get 3 undefined symbols when I try to load the 
>>>module
>>>pvfs.o: unresolved symbol __pollwait
>>>pvfs.o: unresolved symbol mem_map
>>>pvfs.o: unresolved symbol iget4
>>>
>>>The kernel source is installed.
>>>Any idea?
>>>Thanks in advance
>>>Claude
>>>
>>>
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>>>
>>>      
>>>
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>>
>>    
>>
>
>  
>

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