[Bug 1463] New: poor performance with large block size

[samba-bugs at samba.org]

https://bugzilla.samba.org/show_bug.cgi?id=1463

           Summary: poor performance with large block size
           Product: rsync
           Version: 2.6.2
          Platform: x86
        OS/Version: other
            Status: NEW
          Severity: normal
          Priority: P3
         Component: core
        AssignedTo: wayned at samba.org
        ReportedBy: wmatthews at sepaton.com
         QAContact: rsync-qa at samba.org


I have a 29Gig file that is the previous version of a file and a 1.3 Gig 
incremental backup of the file. I did the transfer with no block size option 
and it takes about 6 minutes (GigEthernet). I used --block-size = 90k and it 
took about 6 minutes. I used --block-size=182000 (close to the square root of 
29 Gig) and it only completed ~50 Meg of transfer of the 1.3 Gig in a couple of 
hours.

Chris Shoemaker suggests this is a problem with the sliding window being a 
fixed size of 256k and that the block size will not allow multiple blocks in 
the window size. 

Operating system is Redhat 9.1 for both systems. Both systems have the 2.6.2 
with only 1 patch and it is the one Wayne provided for --bwlimit being bi-modal

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