On Tuesday 14 December 2004 06:31, firnnauriel wrote: > 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. More likely for architectural problems... Does that mean that page fault is 24x slower on UML, or does the index scales nonlinearly? > But the question is, why is > the memcpy on UML (668.4 MB/s) performs faster that > the host OS? ? Maybe less memory pressure in UML... could you make sure you are running that on similarly loaded systems?
Otherwise, this could be related to you using HIGHMEM on the host (?) (might try it with HIGHMEM disabled on the host). No clear light on this, however. > 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! -- Paolo Giarrusso, aka Blaisorblade Linux registered user n. 292729 http://www.user-mode-linux.org/~blaisorblade ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://productguide.itmanagersjournal.com/ _______________________________________________ User-mode-linux-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user
