On 07/25/2007 10:33 AM, [email protected] wrote:
I haven't used swap prefetch either, the call was put out for what
could be used to test the performance, and I was suggesting a test.
if nobody else follows up on this I'll try to get some time to test it
myself in a day or two.
this assumes that this isn't ruled an invalid test in the meantime.
Let's save a little time and guess. While two instances of the hog are
running no physical memory is free (as together they take up 1.5x physical)
meaning that swap-prefetch wouldn't get a change to do anything and wouldn't
make a difference. As such, the two instances test as you suggested would in
fact not be testing anything it seems.
However, if you quit one, and idle long enough to continue with the other
one until swap-prefetch prefetched all its memory back in, it should be a
difference on the order of minutes, even total if swap prefetch fetched it
back in without seeking al over swap-space, and "total" isn't applicable if
the idle time really is free.
A program randomly touching single pages all over memory is a contrived
worst case scenario and not a real-world issue. It is a boundary condition
though, and it's simply quite impossible to think of any example where
swap-prefetch would _not_ give you a snappier feeling machine after you've
been idling.
So really the only question would seem to be -- does it hurt any if you have
_not_ been?
Rene.
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