[ sorry 'bout the latency. this got buried, unfortunately. ] On Wed, 2009-03-11 at 22:23 +0100, Frank Mehnert wrote: > Hi Brian,
Hi Frank, > On Sunday 08 March 2009, Brian J. Murrell wrote: > > > * Check the disk settings in the guest: Does the guest drive the > > > hard disk in DMA mode or PIO mode? > > > > Hrm. How do I determine that from Windows XP? > > Open the device manager and right click on the IDE controller > channel 0. You should find a page where the transfer mode is > shown. OK. Right-clicked IDE ATA/ATAPI controllers->Primary IDE Channel. In Advanced Settings there are boxes for Device 0 and Device 1. Both are set to Transfer Mode: DMA if available and Device 0 says Current Transfer Mode: Multi-Word DMA Mode 2. > > > > The Session Information shows: > > DMA Transfers 492,884 > > PIO Transfers 59,770 > > Data Read 5,062,400,000 B > > Data Written 2,773,438,000B > > Hmm, som PIO transfers but much more DMA transfers. I assume the > count of the PIO transfers does not increases during the benchmark, > does it? Before benchmark: DMA Transfers: 258,713 PIO Transfers: 32,462 After: DMA Transfers: 275,468 PIO Transfers: 32,990 > VBox should definitely make use of multiple cores. Although it supports > only one guest CPU, intensive I/O will benefit from multiple cores as > most devices have dedicated worker threads. Just as I would have thought. > When is one CPU pegged at 100%? Using top, I can only see the "%" of CPU being used as a total of both cores. Virtualbox runs with ~100% (which correlates to a single core) all of the time, not just when running a disk benchmark. > The whole time or only during the benchmark? Whole time. I'm just chasing down this disk benchmark avenue at somebody's suggestion that guest disk i/o might be what is causing all of the CPU use of a VM. Cheers, b.
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