Test RAM read/write speed

[Ssagarr Patil]

Hi,

----------------------------------------
> Date: Tue, 30 Sep 2014 17:49:42 +0200
> Subject: Re: Test RAM read/write speed
> From: peter.senna at gmail.com
> To: Valdis.Kletnieks at vt.edu
> CC: hugarsagar at outlook.com; kernelnewbies at kernelnewbies.org
>
> I use the memtest86+ numbers about memory speed. It gives numbers for
> RAM and different cache levels.
>
you mean numbers for read/write ?

> On Mon, Sep 29, 2014 at 11:42 PM, <Valdis.Kletnieks at vt.edu> wrote:
>> On Tue, 30 Sep 2014 02:53:05 +0530, Ssagarr Patil said:
>>
>>> Is there any benchmarking tool to test read/write speed on Linux and which works on ARM ?
>>
>> This is always a hairy problem. Do you care about the memory speed of the
>> DIMM, or the actual *effective* memory speed? They can be very different,
>> due to the effects of L1/2/3 cache (both positive if there's a cache hit,
>> and negative if you need a cache line load, or if you need a line load
>> that requires a cache line writeback first), whether or not you have
>> a TLB active, and whether *that* has a hit or miss (which varies considerably
>> if you're walking an array and hitting a miss every 4K bytes, versus
>> walking a nest of pointers where you get a TLB miss almost every reference),
>> and a bunch of other issues I lack the caffeine to enumerate...
>>
>> And of course, the *effective* speed (which is what you should probably care
>> about rather than the *rated* speed) will differ based on workload due to
>> the factors listed above....
>>
May be a tool is needed at uboot level to test the speeds.

Thanks.
--Sagar

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>
>
> --
> Peter
>
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