Re: MacOS X equivalent of swapon/swapoff?
Re: MacOS X equivalent of swapon/swapoff?
- Subject: Re: MacOS X equivalent of swapon/swapoff?
- From: John Francini <email@hidden>
- Date: Wed, 11 Oct 2006 08:31:34 -0400
Title: Re: MacOS X equivalent of
swapon/swapoff?
Interesting.
I hadn't thought about it that way; I guess I was still going by
the 'old school' idea that there might be times when a process would
be completely paged out (in other words, *swapping* rather than
paging), and that therefore contiguous disk space would have been a
good thing.
john
At 21:37 -0700 10/10/06, Tim Seufert wrote:
On Oct 10, 2006, at 11:19 AM, John
Francini wrote:
Now if only Darwin would support proper
swap partitions (to ensure that the pagefile was contiguous and
to remove filesystem I/O overhead), I'd be a happy camper.
Contiguous pagefiles make no difference
in real world VM loads. Contiguous files are only important when
accessing large chunks of contiguous data. VM access patterns
are the exact opposite of that - tons of tiny I/Os to random
locations. So it just doesn't matter, because no matter how
contiguous the pagefile, there's going to be tons of seeks anyways.
Only a truly pathologically fragmented pagefile could hurt
performance. (IIRC Darwin uses clusters of four pages as its
atomic unit of pagefile access, so there'd have to have a significant
number of those 16KB clusters fragmented before you'd notice a
performance hit.)
Filesystem overhead is also unlikely to
be an issue. Once all the metadata is in cache it should
disappear into the noise.
--
John Francini, email@hidden
"The journey
is more important than the destination-that's part of life. If you
only live for getting to the end, you're almost always
disappointed." -Donald
Knuth
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