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Re: How to estimate System Memory Bandwidth by sampling

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From	Rainer Weikusat <rweikusat@mssgmbh.com>
Newsgroups	comp.os.linux.development.system
Subject	Re: How to estimate System Memory Bandwidth by sampling
Date	Fri, 15 Jul 2011 16:24:31 +0100
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Tim Roberts <timr@probo.com> writes:
> Rainer Weikusat <rweikusat@mssgmbh.com> wrote:
>>Why this? All which seems to be needed for that is access to an area
>>of physical memory configured as uncached and some hardware
>>timer that can be used to measure the time it takes to execute some
>>'block memory access loop'.
>
> Assuming you stopped all of the other CPUs and blocked any peripherals that
> might do DMA, you could compute the bandwidth of the path between CPU and
> memory.

Interrupts would need to be disabled, too. But in practice, that's
easier to do than it seems: Take the system into 'single user mode'
and disconnect any kind of network. This should at least result in a
useful approximation.

[...]

> More importantly, however, there is still no way to find out "how much
> bandwidth was used in the last N milliseconds".  That's what he wanted to
> find out.

Ok, I misread that ...

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Thread

How to estimate System Memory Bandwidth by sampling Xiaofeng Ye <yexfeng@gmail.com> - 2011-07-10 20:20 -0700
  Re: How to estimate System Memory Bandwidth by sampling Tim Roberts <timr@probo.com> - 2011-07-13 00:01 -0700
    Re: How to estimate System Memory Bandwidth by sampling Rainer Weikusat <rweikusat@mssgmbh.com> - 2011-07-13 13:12 +0100
      Re: How to estimate System Memory Bandwidth by sampling Tim Roberts <timr@probo.com> - 2011-07-14 22:18 -0700
        Re: How to estimate System Memory Bandwidth by sampling Rainer Weikusat <rweikusat@mssgmbh.com> - 2011-07-15 16:24 +0100

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