[j-nsp] understand the DRAM usage on CFEB(FEB-M10i-M7i-S)

[Martin T]

One last question- am I correct that copy of FIB is kept on this
microkernel SDRAM? I mean there seems to be a clear correlation
between amount of routes in router and CFEB microkernel memory
utilization. The reason I assume this is because if I upgrade the
SDRAM SODIMM on CFEB(i.e. upgrade the memory for microkernel), then
total amount of "heap" memory on CFEB increases and if router has more
routes, then the usage of "heap" memory increases.


thanks,
Martin

On 9/30/15, Martin T <m4rtntns at gmail.com> wrote:
> Ok, thanks! I had never seen a solution where parity information is
> stored in additional individual SDRAM chips. So in conclusion 128MiB
> of on-board SDRAM is used for packet memory, 64MiB of on-board SDRAM
> is used for packet memory parity information and replaceable DDR SDRAM
> SODIMM is used solely for the PFE microkernel.
>
>
> regards,
> Martin
>
> On 9/29/15, Michael Loftis <mloftis at wgops.com> wrote:
>> The "extra" SDRAM chips.  The packet memory has parity or ECC bits, I
>> actually do not recall for sure which, but the "extra" is for those
>> extra bits.
>>
>> On Tue, Sep 29, 2015 at 12:45 PM, Martin T <m4rtntns at gmail.com> wrote:
>>> What do you mean?
>>>
>>>
>>> thanks,
>>> Martin
>>>
>>> On Tue, Sep 29, 2015 at 8:45 PM, Michael Loftis <mloftis at wgops.com>
>>> wrote:
>>>> Parity/ECC.
>>>>
>>>> On Tue, Sep 29, 2015 at 7:32 AM, Martin T <m4rtntns at gmail.com> wrote:
>>>>> Hi,
>>>>>
>>>>> according to Juniper M10i Compact Forwarding Engine
>>>>> Board(http://www.juniper.net/techpubs/en_US/release-independent/junos/topics/concept/cfeb-m10i-description.html)
>>>>> documentation it has 128 MiB SDRAM for packet memory and 128 MiB SDRAM
>>>>> for the microkernel. If I visually inspect the CFEB, then it has
>>>>> twelve "MT 46V8M16" DDR SDRAM chips which means 12x 134217728 bits,
>>>>> i.e. 192MiB of on-board soldered DDR SDRAM. Questions:
>>>>>
>>>>> 1) Are four "MT 46V8M16" DDR SDRAM chips actually not in use? If they
>>>>> are in use, then what for?
>>>>>
>>>>> 2) Am I correct that on-board soldered DRAM is used for shared packet
>>>>> buffer and installable DDR SDRAM SODIMM is used for the microkernel?
>>>>>
>>>>>
>>>>> thanks,
>>>>> Martin
>>>>> _______________________________________________
>>>>> juniper-nsp mailing list juniper-nsp at puck.nether.net
>>>>> https://puck.nether.net/mailman/listinfo/juniper-nsp
>>>>
>>>>
>>>>
>>>> --
>>>>
>>>> "Genius might be described as a supreme capacity for getting its
>>>> possessors
>>>> into trouble of all kinds."
>>>> -- Samuel Butler
>>
>>
>>
>> --
>>
>> "Genius might be described as a supreme capacity for getting its
>> possessors
>> into trouble of all kinds."
>> -- Samuel Butler
>>
>