[linux-cifs-client] Re: extremely slow throughput writing to remote

Steve French smfrench at austin.rr.com
Mon May 22 19:33:51 GMT 2006


Just did a quick experiment:

 From my laptop to a home PC over standard 100Mbit ethernet (samba 
3.0.20 on 2.6.17-rc2 with ext3 on a common older IDE drive, WDC 1200JB).

For a 256MB file copy
     "dd if=/dev/zero of=/mnt/tstfile bs=256K count=1000"
cifs vfs (2.6.17-rc2 on client) was 11.2 MB/sec (90 megabits per seconds 
is near maximum wire speed)  vs. Local performance of large file copy 
was over 30MB/sec.  This is in line with what I would expect given the 
wire speed and much longer path lengths and lack of serialization.  Note 
that with

Note that the default block size of 512 that dd uses is atrocious and 
causes cifs to be given very small writes - which is much slower 
(2MB/sec).  Make sure your application is using a block size as least as 
big as the cifs write size (14 pages - ie 56K)

I will retry over gigE on the same two machines in a few minutes.


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