Linked by Thom Holwerda on Tue 17th Nov 2009 16:13 UTC
Windows Microsoft's Professional Developers Conference is currently under way, and as usual, the technical fellows at Microsoft gave speeches about the deep architecture of Windows - in this case, Windows 7 of course. As it turns out, quite some seriously impressive changes have been made to the very core of Windows - all without breaking a single application. Thanks to BetaNews for summarising this technical talk so well.
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RE: Arrggg!
by slight on Tue 17th Nov 2009 19:06 UTC in reply to "Arrggg!"
slight
Member since:
2006-09-10

The nice thing about caches, generally speaking, is that if you need the space for something else you can just discard the cache, so when your programs need that space the cache will be used for the programs.

The chances that you can manage the memory better than the kernel are slim.

There is an argument for how to tune whether very old pages get swapped out though, which Linux exposes through its 'swappiness' parameter (great name that ;)

Reply Parent Score: 2

RE[2]: Arrggg!
by Bill Shooter of Bul on Tue 17th Nov 2009 23:44 in reply to "RE: Arrggg!"
Bill Shooter of Bul Member since:
2006-07-14

I can set the size of the virtual memory page file in windows, or leave it to the default setting. Why can't I also tune this behavior that is essentially controlling similar behavior?

Reply Parent Score: 2

RE[3]: Arrggg!
by PlatformAgnostic on Wed 18th Nov 2009 02:12 in reply to "RE[2]: Arrggg!"
PlatformAgnostic Member since:
2006-01-02

The pagefile size has no effect unless it is set to be too small. The OS will not use the pagefile to store information that could just as well be stored in memory (old modified pages do eventually get written out, but they won't be discarded and read back in unless there's other demand for memory).

Reply Parent Score: 2

RE[2]: Arrggg!
by cb88 on Wed 18th Nov 2009 00:07 in reply to "RE: Arrggg!"
cb88 Member since:
2009-04-23

Actually I'm pretty sure that exokernel designers would differ with your opinion on the kernel being the best at memory management. see here http://pdos.csail.mit.edu/exo.html

The drawback is exokernels have an inherent bloaty tendency that could be avoided though...

Reply Parent Score: 0

RE[3]: Arrggg!
by m_pll on Wed 18th Nov 2009 04:29 in reply to "RE[2]: Arrggg!"
m_pll Member since:
2009-07-16

Deciding what pages to prefetch into unused memory is a difficult problem that requires a lot of high level code that doesn't really belong in the kernel.

And this is precisely why Windows doesn't do this in the kernel. Prefetching decisions are made by the Superfetch service, which runs entirely in user mode. The kernel provides some basic interfaces that Superfetch relies on, but all the logic is in user space.

Reply Parent Score: 4