[Bug 104721] kmail freezes while messages are moved to another dir

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http://bugs.kde.org/show_bug.cgi?id=104721         




------- Additional Comments From isj-bugzilla i1 dk  2007-07-15 15:20 -------
(KDE 3.5.1, KMAIl 1.9.1)

maildir<->maildir move is not that fast either.

Moving 6309 messages between 2 NFS maildirs took several minutes and consumed considerable network bandwidth:

Before:
# ip -s link show dev lan1
2: lan1: <BROADCAST,MULTICAST,UP> mtu 6000 qdisc pfifo_fast qlen 1000
    link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff
    RX: bytes  packets  errors  dropped overrun mcast   
    272590096  213635   0       0       0       1      
    TX: bytes  packets  errors  dropped carrier collsns 
    210820280  213657   0       0       0       0      
After:
# ip -s link show dev lan1
2: lan1: <BROADCAST,MULTICAST,UP> mtu 6000 qdisc pfifo_fast qlen 1000
    link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff
    RX: bytes  packets  errors  dropped overrun mcast   
    450667222  392535   0       0       0       1      
    TX: bytes  packets  errors  dropped carrier collsns 
    363576848  392555   0       0       0       0      

178MB read, 152MB write.
Since message can be moved between maildirs on the same device with a simple rename, this is inefficient.

For comparison:
A simple 'mv' of 6309 files took 20 seconds,
# ip -s link show dev lan1
2: lan1: <BROADCAST,MULTICAST,UP> mtu 6000 qdisc pfifo_fast qlen 1000
    link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff
    RX: bytes  packets  errors  dropped overrun mcast   
    459172546  419878   0       0       0       1      
    TX: bytes  packets  errors  dropped carrier collsns 
    372514124  419896   0       0       0       0      
isjsys:~ # ip -s link show dev lan1
2: lan1: <BROADCAST,MULTICAST,UP> mtu 6000 qdisc pfifo_fast qlen 1000
    link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff
    RX: bytes  packets  errors  dropped overrun mcast   
    465899264  451431   0       0       0       1      
    TX: bytes  packets  errors  dropped carrier collsns 
    377347846  451449   0       0       0       0      

= 6MB read, 5MB write

(Yes, I know that KMail needs to update the index too, but still...)