Re: Constrained virtual machines

Karanbir Singh wrote:
> does vmware-server ( also, like vmware-player, free to download and use 
> ) not meet your requirement ?

I think he has got that already. He wants fine-grained cpu and other 
resource control for testing. vmware-server only offers very crude cpu 
control (1 processor, 2 processors...) although the memory allocated can 
be fine-grained.

J
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Subversion Repository Searcher

Hello,

I've been asked to write a tool that will search documents in a
subversion repository by keyword and return the document names which
match.

Is there some kind of plug-in that would do this?  Or will I have to
write this myself?  The documents are word documents, but I already
have code that will do regex matching on word documents.

One question concerns how to address the repository.  I don't want to
have to check out the documents and then search them, or run a
parallel database - but I am not sure how programatically to search
objects inside a repository.

Any ideas / suggestions?

S
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Re: Constrained virtual machines

On Thu, Nov 30, 2006 at 03:05:11PM +0000, Richard Huxton wrote:
> Is anyone using VM technology that provides limits on CPU and I/O as 
> well as memory usage?

Be aware that disk performance under any VM I've seen sucks compared
to the real hardware ...  So if you're testing a database, where disk
I/O performance really matters, it's not clear the test will be fair.

Rich.

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Re: Subversion Repository Searcher

On 01/12/06, Steve Nelson <sanelson <at> gmail.com> wrote:
> Hello,
>
> I've been asked to write a tool that will search documents in a
> subversion repository by keyword and return the document names which
> match.
>
> Is there some kind of plug-in that would do this?  Or will I have to
> write this myself?  The documents are word documents, but I already
> have code that will do regex matching on word documents.
>
> One question concerns how to address the repository.  I don't want to
> have to check out the documents and then search them, or run a
> parallel database - but I am not sure how programatically to search
> objects inside a repository.
>
> Any ideas / suggestions?
>
> S

Hmm

You can access SVN via http. just point you web browser at the repository.

So you should be able to writing somthing in your favorate scripting
language to do the searching. Thats so long as your subversion
repositatry is stored using Web Dav which is normally true.

You might even be able to use a standard web searching engine there
are quite a few around.

Re: Constrained virtual machines

> On Thu, Nov 30, 2006 at 03:05:11PM +0000, Richard Huxton wrote:
>> Is anyone using VM technology that provides limits on CPU and I/O as
>> well as memory usage?
>
> Be aware that disk performance under any VM I've seen sucks compared
> to the real hardware ...  So if you're testing a database, where disk
> I/O performance really matters, it's not clear the test will be fair.

As a counter example, the PC emulator on the Archimedes used to clock disk
access something like 25 times as fast as a native PC could manage at the
time.  This was because the ARM was fast enough to read the disc
continually, at a time when the Intel family still needed to use
interleave to keep up.

Not really relevant nowadays I suppose.  

John

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Re: Subversion Repository Searcher

Steve Nelson wrote:
> One question concerns how to address the repository.  I don't want to
> have to check out the documents and then search them, or run a
> parallel database - but I am not sure how programatically to search
> objects inside a repository.
> 
> Any ideas / suggestions?

while this does not really relate to your question directly.... svn has 
nice python bindings that will let you do pretty much anything, 
including trawl the repo for fluff...

if you cant run the 'tool' on the svn repo host machine, maybe a 
mod_python driven web interface that can ? ( eg. Trac source is mostly 
human parseable, and uses the svn_py bindings extensively )

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Re: Constrained virtual machines

James Roberts wrote:
> Karanbir Singh wrote:
>> does vmware-server ( also, like vmware-player, free to download and 
>> use ) not meet your requirement ?
> 
> I think he has got that already. He wants fine-grained cpu and other 
> resource control for testing. vmware-server only offers very crude cpu 
> control (1 processor, 2 processors...) although the memory allocated can 
> be fine-grained.

Yeah - what I'd like to be able to do is have a virtual-machine limited 
to e.g. the speed of a 1GHz P4 with 512MB RAM and something that looks 
like a single IDE disk. And then change all those parameters on the next 
test run. And it needs to be *all* of them, otherwise the tests will be 
unbalanced.

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Re: Constrained virtual machines

Richard Jones wrote:
> On Thu, Nov 30, 2006 at 03:05:11PM +0000, Richard Huxton wrote:
>> Is anyone using VM technology that provides limits on CPU and I/O as 
>> well as memory usage?
> 
> Be aware that disk performance under any VM I've seen sucks compared
> to the real hardware ...  So if you're testing a database, where disk
> I/O performance really matters, it's not clear the test will be fair.

Ah, but I don't care if disk access is 10 times slower than for-real. So 
long as I can then scale CPU and memory by the relevant amount to keep 
things balanced.

I'm not interested in absolute performance figures but the interplay 
between (virtual) hardware and database configuration.

As you point out, disk performance does seem to suck with VMs 
(understandable) which with an unconstrained VM would mean the effects 
of disk-cache would be out of proportion to the effects on a "real" server.

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Re: Constrained virtual machines

Richard Huxton wrote:
> James Roberts wrote:
>> Karanbir Singh wrote:
>>> does vmware-server ( also, like vmware-player, free to download and 
>>> use ) not meet your requirement ?
>>
>> I think he has got that already. He wants fine-grained cpu and other 
>> resource control for testing. vmware-server only offers very crude cpu 
>> control (1 processor, 2 processors...) although the memory allocated 
>> can be fine-grained.
> 
> Yeah - what I'd like to be able to do is have a virtual-machine limited 
> to e.g. the speed of a 1GHz P4 with 512MB RAM and something that looks 
> like a single IDE disk. And then change all those parameters on the next 
> test run. And it needs to be *all* of them, otherwise the tests will be 
> unbalanced.
> 

you are not going to get such exact throttling controls anywhere ( that 
i am aware of ), but your closest match is going to be Xen.

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Re: Constrained virtual machines

On Fri, Dec 01, 2006 at 10:44:02AM +0000, Richard Huxton wrote:
> Richard Jones wrote:
> >Be aware that disk performance under any VM I've seen sucks compared
> >to the real hardware ...  So if you're testing a database, where disk
> >I/O performance really matters, it's not clear the test will be fair.
> 
> Ah, but I don't care if disk access is 10 times slower than for-real. So 
> long as I can then scale CPU and memory by the relevant amount to keep 
> things balanced.

Actually I'm afraid that the effects might be more subtle than that.
Remember that disk I/O isn't just "XX megabytes/sec".  It's a complex
mixture of types of operation, each having their own latency,
throughput and other peculiarities.  I would expect[1] that if issuing
commands directly over SATA to a directly connected disk you would
expect to see an entirely different set of results from issuing
commands through a hypervisor into a contended host domain and then
down to disk.  The latencies I would expect to be considerably
greater, but effects like disk seek times would be lost in the noise,
and throughput would be reduced by only a constant factor.  Be
interesting to see some real world tests through ...

Rich.

[1] But cannot prove - ask Dan Berrange, he's the local Xen guru 

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