[OpenAFS-devel] how does fileserver read from disk?

[Roland Kuhn]

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Dear experts!

Having just strace'd the fileserver (non-LWP, single-threaded) on  
Linux, I noticed that the data are read from disk using readv in  
packets of 1396bytes, 16kB per syscall. In the face of chunksize=1MB  
from the client side this does not seem terribly efficient to me, but  
of course I see the benefit of reading chunks which can readily be  
transferred. If my interpretation is wrong or this is an artifact of  
not using tviced, please say so (if possible with a short reference  
to the source), otherwise it would be nice to know why the fileserver  
cannot read(fd, buf, 1048576) as that would give at least one order  
of magnitude better performance from the RAID and (journalled)  
filesystem.

Ciao,
                     Roland

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