How to measure the RAM read/write performance

[sandeep kumar]

>1. use early_param to get the physical start address and size of
test_region, or you can just ignore this step and hard code to 510M and 2M
for test purpose only.

>2. use ioremap_nocache() to map this region to a virtual region. note that
this funtion may fail if you are asking a very large vitual memroy region.

Sounds good, i am gonna try this and let you know.. :)


On Wed, Feb 27, 2013 at 8:19 PM, buyitian <buyit at live.cn> wrote:

> ----------------------------------------
> > From: buyit at live.cn
> > To: coolsandyforyou at gmail.com; kernelnewbies at kernelnewbies.org
> > Subject: RE: How to measure the RAM read/write performance
> > Date: Wed, 27 Feb 2013 22:33:15 +0800
> > CC: dhylands at gmail.com
> >
> > ________________________________
> > > From: coolsandyforyou at gmail.com
> > > Date: Tue, 26 Feb 2013 17:01:54 +0530
> > > Subject: How to measure the RAM read/write performance
> > > To: kernelnewbies at kernelnewbies.org
> > > CC: dhylands at gmail.com
> > >
> > > Hi All
> > > In performance benchmark tools, When we profile read/write timings
> > > mostly, those read/writes are done to cache only.
> > >
> > > I want to measure my DDR(RAM chip) performance.
> > > So i want to make sure, every read/write should happen to DDR RAM chip
> only.
> > >
> > > How can i achieve this...Any ideas/suggestions...?
> >
> > try to reserve a large region from bootloader(L4 in Qualcomm platform),
> let's say it is 10MB continuous physical memory.
>
> sorry, to be accurate, reserve physical memory is done by kernel cmdline,
> this cmdline parameter can be passed from L4 to kernel, or configed by
> kernel itself.
> the cmdline will be like below:
> mem=510M at 0 test_region=2M at 510M
>
> above example tells kernel you have totally 512MB physical memory, but
> kernel will only use the first 510MB, the latter 2MB memory is used by you.
> how to map and use this region depends on you.
>
> > in kernel, map this region to an continuous virtual region, note that
> the pgprot should be uncachable since you want to test without cache.
>
> 1. use early_param to get the physical start address and size of
> test_region, or you can just ignore this step and hard code to 510M and 2M
> for test purpose only.
>
> 2. use ioremap_nocache() to map this region to a virtual region. note that
> this funtion may fail if you are asking a very large vitual memroy region.
>
> > once you configed like this, you can read/write to this vitual region
> without data cache invovled.
> >
> > >
> > > --
> > > With regards,
> > > Sandeep Kumar Anantapalli,
> > >
> > > _______________________________________________ Kernelnewbies mailing
> > > list Kernelnewbies at kernelnewbies.org
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>
>



-- 
With regards,
Sandeep Kumar Anantapalli,
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