Re: Despite promises, VPC 7 is impossibly slow... (TESTS Needed)

From: John McGhie (john_at_mcghie.name)
Date: 01/29/05 

Date: Sat, 29 Jan 2005 16:35:03 +1100

Hi Jim:

I am not sure that I understood Scottie's post. He seems to be advocating
turning Virtual Memory off in OS X. I was not aware that you could do that:
I certainly do not know how. My information is that the Mach kernel
requires VM, and will not start or run if it's not there :-)

I also believe that some versions of OS X.3 seem to be having problems with
their virtual memory management. They seem to create multiple temporary
paging files, then "forget" to release them. It seems to be a good idea to
reboot OS X every week or so to force it to let these paging files go and
clean up its temporary storage. I would recommend that you try a cold start
of OS X. It can result in quite a speed improvement, and if it does, the
speed improvement in Windows will be a lot larger. Remember that before
Windows can do "anything", it must wait for OS X to finish paging.

In Windows, there were two tricks you could play with virtual memory to
speed it up: neither is available in Virtual PC. The first was to put the
paging file on a different physical volume from either the OS or the
applications. The second was to allocate the paging file to a partition of
its own, so it could never become fragmented.

Since the entire virtual PC is a single file on the Mac, you cannot send the
page file to a different device: I don't know whether Windows will allow you
to set the page file to the Mac drive, but I am pretty sure it won't because
the Mac drive is treated as a Network drive, and Windows requires the page
file to be on a local disk.

You could set the VM minimum and maximum sizes to the same value. You could
also set both to 0 (which disables virtual memory in Windows).

Setting the page file minimum and maximum sizes to the same value might be
worth trying. It will cause Windows to start slower than normal, because it
has to allocate the entire page file at startup. But it would then remove
the small overhead Windows requires to manage the page file size.

The rule of thumb for Windows is "set the total paging space to 2.5 times
the physical memory." There is a further consideration in Windows: there
must be at least 64 MB of virtual memory available to enable a memory dump
for debugging, and that allocation must be on the same volume as the
operating system kernel. If you have full memory dump available, the
allocation must be at least a megabyte larger than the physical RAM.

Setting the page file to 0 is an extremely risky move. If you do not have
enough physical memory, and no swap file, Windows won't boot. Because it
won't boot, you can't fix it. Your virtual PC, all of its data, and all of
its applications would now be trash: nothing to do but delete the thing and
start again. I have booted Windows XP without a swap file in 256 MB of
physical RAM on a physical PC. I would never try it with less.

Hope this helps

On 29/1/05 10:19 AM, in article
1106954366.474061.173420@f14g2000cwb.googlegroups.com, "babcoc2@hotmail.com"
<babcoc2@hotmail.com> wrote:

> Scotti: I tried your suggestion #2 below... I set the initial swap page
> size to the recommended size, then made the MAX size the same...
>
> I had trouble with the ONLY app I *need* to use in VPC; IE 6.0 SP1. Why
> this IE? Well the Web app I hook up to requires MSFT's VM machine and
> JAVA system to run. Safari (Panther) won't do it. Safari still does NOT
> support 'Live Connect' well enuff for the Web app I need to work
> correctly.
> The app *says* it supports Sun's JAVA 1.3.1 in W2K, but I can't get
> that to run with the app at all.
>
> IE had trouble infrequently; incomplete rendering of page data ..
> After I reverted BACK to initial swap, then 2X that for max, things
> really took off and I had no problems in rendering the displays. Also I
> run NO other MAC OS X apps except Virex 7.2 and BrickHouse firewall.
>
> I run VPC 6.1.1/Windows2000. Mac is G4 Graphite with 704MB, a fast
> (7200rpm) 80 GB dis,k and I give about HALF the real memory to VPC/W2K.
>
> Turning off Firewall with the first config (equal initial & Max) still
> showed errors in rendering. (Haven't tried disabling Virex.. should
> that help?) On W2K I run McAfee's anti-virus V 8.0 and no W2K firewall
> software.
>
> So, in reference to Suggestion #2 below, what is the correct algorithm
> for setting the initial swap size and the Max swap size. Use the
> recommendaed size for initial and Max? (unfortunately, That is what got
> me into trouble).
>
> Your suggestion(s) made sense, but not for me.. Thanks anyhow for your
> efforts.
>
> Cheers, Jim B
> PS I had NO problems in page loading speed as jac did
> PPS Earlier in a Connectix forum, advice was to give about 1/3 of your
> real memory to VPC.
> With Panther, newer G models, lots more memory, I am not sure
> that still holds, do you?
> ------------------------------------------------------------------------------
> -------
> Scottie wrote:
>> "jac" <jcoronat@paulbunyan.net> wrote in message
>> news:1106637173.254367.260100@f14g2000cwb.googlegroups.com...
>>> I've got Windows set to optimize speed: control
> panel>system>advanced
>>> (tab)>performance, (all of them), paging file size = 384 MB,
> expandable
>>> to 768 MB, and so on. It may take a good minute to load a page
> that's
>>> on my own MacOS drive using IE. Networking is set to Virtual
> Switch.
>>> The allocation it gives itself in my memory continues to grow: it
>>> started at about 290 MB and now it's up around 370 MB. What's with
>>> that? If anybody has any suggestions, please let me know!
>>
>> Problem #1: youre using Virtual Memory (Swap File) when perhaps you
> dont
>> have to.
>> Virtual Memory means your system is writing to and
>> reading from disk
>> data that should be in memory - thus you will S L
> O W
>> down a lot.
>> (I know most people will advise you to set RAM to
> 256MB
>> and use
>> virtual memory... if that works great, but it
> wont
>> always do so, especially
>> if you need more than 256MB of memory with your
> current
>> load.)
>>
>> Suggestion for #1: Increase the memory you allocate to VPC. How much
> do you
>> need?
>> if 370MB is as high as it gets, then you may not
> need to
>> max it out to 512MB
>> but I recommend you give at least 384MB with the
> load
>> your reporting,
>> but make sure you dont see hard paging activity
> becoming a
>> regular event.
>>
>> If you can turn off Virtual Memory ...
>> Disclaimer: be careful when doing this.. if your
> load
>> ever needs more than the
>> amount of physical RAM you've allocated your in
> trouble.
>> Thats why I do give 512MB contrary to other advice.
> It
>> depends, ymmv.
>> I have > 1GB of physical RAM so I can do that if
> you have
>> less than this
>> then you have to be concerned with how much memory
> youre
>> leaving OS X.
>> No point in trying to avoid swapping in VPC if OS X
> swaps
>> like crazy.
>> So if you only have 512MB total memory in OS X e.g.
> , I
>> suggest you
>> get more memory.
>>
>> Problem #2: Youre virtual memory settings are adjustable
> (384MB-768MB).
>> This is a big mistake.
>>
>> Suggestion for #2:
>> If youre going to use Virtual Memory then set the
> min
>> and max value to the
>> same value.
>> This will avoid Windows constantly resizing the
> swap
>> file up and down based
>> on its judgement of memory usage.
>> Virtual Memory is a big overhead in itself even
> with a
>> fixed swap file size,
>> allowing it to adjust adds even more overhead.
>> Remember, in VPC the route to better performance
> is to
>> reduce or eliminate
>> overhead processing thats not necessary.
>>
>> Suggestion for #1 &/or #2:
>> If you are swapping (even if you arent) then
> consider
>> getting a faster hard drive.
>> A 4200rpm drive in a pb or ibook is going to be
> pretty
>> bad.
> 

-- 
Please reply to the newsgroup to maintain the thread.  Please do not email
me unless I ask you to.
John McGhie <john@mcghie.name>
Consultant Technical Writer
Sydney, Australia +61 4 1209 1410

Relevant Pages

  • Re: Too Much Memory
    ... Slow performance resulting from insufficient memory, ... on virtual memory, ... may be especially noticed by those upgrading to Windows XP from an earlier ... You can have too many programmes running in the background. ...
    (microsoft.public.windowsxp.perform_maintain)
  • Re: Too many processes?
    ... Or are you actually seeing a capacity-related error message? ... The number of processes, qua *processes*, that can be created by Windows XP is limited only by the number of available process handles. ... the Windows linker assigns 1 MB of stack memory to each thread. ... this comes back to the old dichotomy between REAL memory and VIRTUAL memory. ...
    (microsoft.public.windowsxp.general)
  • Re: Usable RAM
    ... How about using Windows XP x64? ... The rest gets taken by such items as shared memory on the graphics ... Photoshop says that the available RAM is 1.711GB. ... you will never get to use the full 4gb virtual memory because ...
    (microsoft.public.windowsxp.general)
  • Re: Page file growing out of control
    ... "Virtual Memory in Windows XP" ... internet connection the CPU usage immediately soared to 100% for about 15 ...
    (microsoft.public.windowsxp.general)
  • Re: memory requirements of closed vs quit apps
    ... majority of programs remain open when all their windows are closed. ... they use bugger all memory - and are ... individual apps Real and Virtual memory entries. ... In order to push it out to swap, ...
    (uk.comp.sys.mac)