Re: How to estimate System Memory Bandwidth by sampling

From	Tim Roberts <timr@probo.com>
Newsgroups	comp.os.linux.development.system
Subject	Re: How to estimate System Memory Bandwidth by sampling
Date	2011-07-14 22:18 -0700
Organization	Providenza & Boekelheide, Inc.
Message-ID	<96jv175030s6dgs36egstrgvg9bi8mk9rf@4ax.com> (permalink)
References	<cff4b142-7330-4913-b122-b69b4b430d28@s33g2000prg.googlegroups.com> <92gq1790rij00c57o68guvvjjpmpa9qmu0@4ax.com> <87mxgi4bxk.fsf@sapphire.mobileactivedefense.com>

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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.  However, that's not the "total memory bandwidth."

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.
-- 
Tim Roberts, timr@probo.com
Providenza & Boekelheide, Inc.

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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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