Re: [Xen-users] Differences in performance between file and LVM based images

[Javier Guerra <javier@xxxxxxxxxxx>]

On Thursday 24 August 2006 9:06 am, Petersson, Mats wrote:
> Yes, you'll probably get file-caching on Dom0 when using file-based
> setup, which doesn't happen on other setups.

it's also interesting to see that even in the 'base' tests, throughput is 
higher in LVM than partition, and file is higher than LVM.  that sure means 
that this specific test is benefited by extra levels of 
abstraction/reordering/caching

> The following would be interesting to also test:
> 1. Test with noticably larger test-area (say 10GB or so).

1GB devices are much bigger then usual units (4M for LVM, 512-4K for files), 
but with 8GB of RAM, it really looks small.  also, recently there have been 
some questions about minimal RAM form dom0, with 64M-256M common in x86-32 
and 256M-512M for x86-64.  (and corresponding laments on the increased 
requirements)

> 2. Test multiple domains simultaneously to see if file-based approach is
> still the fastest in this approach.

this would be really interesting, i would guess that on single drive setups, 
both LVM and partition would suffer from the longer head seeks.  in some 
cases it might help if the filebacks are heavily fragmented!

> 3. Test the new (unstable) Blktap model.

Blktap?  care to expand on this?

-- 
Javier

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