bcopy's performance on 2.4.20 (Redhat) and 2.40.20-8um (UML)

bcopy's performance on 2.4.20 (Redhat) and 2.40.20-8um (UML)

[firnnauriel]

Greetings to all! I would like to ask for your advice
regarding this question:
 "In general, is the memcpy"s performance on UML (User
 Mode Linux) environment better than the host OS? If
 that is the case, can you give the reason behind it
 (ex. UML"s architecture)?"
 
 Here"s the evironment:
 HOST
 OS: Redhat 9 (kernel 2.4.20-8)
 Brand/Model: Dell PowerEdge 2600
 CPU: Intel Xeon 2.4 GHz
 Memory: 2 GB
 Disk Space: 73 GB
 
 UML
 Kernel version    : 2.40.20-lsm1-8um 
 Allocated Mem     : 256MB
 
 I used lmbench-2.0.4 for the bandwith and latency
 testing. here"s the result:
 
 host
 memcpy     : 597.1  MB/s (higher is better)
 page fault : 2.00000     (smaller is better)
 
 uml
 memcpy     : 668.4
 page fault : 48.0
 
 The result in page fault might be because of low
 memory allocated in UML. But the question is, why is
 the memcpy on UML (668.4 MB/s) performs faster that
 the host OS?
 
 I already asked the developer of lmbench, and he
 adviced me to ask this question to the linux kernel
 mailing list.
 
 I would really appreciate any inputs and advice.
Thank
 you!


		
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