Re: dynamic_pager and context switching
Re: dynamic_pager and context switching
- Subject: Re: dynamic_pager and context switching
- From: Brian Bergstrand <email@hidden>
- Date: Sun, 8 Feb 2004 18:39:33 -0600
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I believe (someone correct me if I'm wrong) that dynamic_pager acts
like an nfsd process. Upon launch, it immediately makes a syscall and
never returns. So it's basically a process wrapper around a kernel
thread that never exits the kernel. Hence, I don't think there is much
context switch overhead (besides a thread switch within the kernel
[stack and registers]).
HTH.
On Feb 8, 2004, at 5:44 PM, Brian Tabone wrote:
>
I was digging through the darwin kernel lists, and did some cursory
>
searches on developer.apple.com, but I didn't find the answer. My
>
question is , does the kernel turn to dynamic_pager every time it
>
swaps pages in and out, or does dynamic_pager simply manage the swap
>
file(s) and grow/shrink them based on usage by the kernel? The reason
>
I ask is that it would seem a large performance penalty to have to
>
context switch out to a user-space daemon for every page in/out
>
request. Not only would you be contesting with page swaps, but you
>
would further be slowed down by expensive context switching from
>
kernel to user space.
>
>
Thanks in advance,
>
-Brian T
>
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Brian Bergstrand <
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