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

[Chris Shoemaker]

On Wed, Jun 16, 2004 at 06:21:15AM -0700, samba-bugs at samba.org wrote:
> 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. 

Er, that suggestion sounds WAY too intelligent to have come from me.  :-)
Seriously, that was Craig Barratt.
-chris

> 
> 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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