On 09/23/2009 06:58 PM, Matthew Tippett wrote:
Hi,
I would like to call attention to the SQLite performance under KVM in
the current Ubuntu Alpha.
http://www.phoronix.com/scan.php?page=article&item=linux_2631_kvm&num=3
SQLite's benchmark as part of the Phoronix Test Suite is typically IO
limited and is affected by both disk and filesystem performance.
When comparing SQLite under the host against the guest OS, there is
an order of magnitude _IMPROVEMENT_ in the measured performance of
the guest.
I am expecting that the host is doing synchronous IO operations but
somewhere in the stack the calls are ultimately being made
asynchronous or at the very least batched for writing.
On the surface, this represents a data integrity issue and I am
interested in the KVM communities thoughts on this behaviour. Is it
expected? Is it acceptable? Is it safe?
qemu defaults to write-through caching, so there is no data integrity
concern.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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