get_cycles/get_tbl on 405

3 messages, 3 authors, 2001-08-25 · open the first message on its own page

get_cycles/get_tbl on 405

From: andrew may <hidden>
Date: 2001-08-24 01:59:11

I wanted to do some quick time measurements of some things on a driver
running of the 405GP and I eneded up using get_tbl(). It seems like
get_cycles should be the more standard way to get a tick count but
it seems to return 0. I don't get the __ftr_fixup stuff in timex.h
so I am not sure what it is trying to do differently from get_tbl.


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Re: get_cycles/get_tbl on 405

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2001-08-24 09:52:56

I wanted to do some quick time measurements of some things on a driver
running of the 405GP and I eneded up using get_tbl(). It seems like
get_cycles should be the more standard way to get a tick count but
it seems to return 0. I don't get the __ftr_fixup stuff in timex.h
so I am not sure what it is trying to do differently from get_tbl.
The __ftr_fixup in timex.h adds a reference to this code in the
feature fixup section. This allow the code that access the TB to
be nop'ed out on CPUs that don't implement it (601)

Ben.


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Re: get_cycles/get_tbl on 405

From: Dan Malek <hidden>
Date: 2001-08-25 02:35:10

andrew may wrote:
I wanted to do some quick time measurements of some things on a driver
running of the 405GP and I eneded up using get_tbl(). It seems like
get_cycles....
Hmmm....these look like they should work exactly the same.....
It would help me if you could disassemble a little code snippet
around the place you use these so we could have a look.

Thanks.


	-- Dan

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