Howto place.localfar in MSM instead of L2?

Clemens Eisserer

Hi,

We are currently working on an application which makes extensive use of L2 memory, the more the better.

Running on the C6678 using OpenMP for parallelization, a section named ".localfar" almost occupies 25% of the total L2 memory:

00800000    00800000    0005d030   0005d02c    rw-
00800000    00800000    0005d02c   0005d02c    rw- .pfeheap_iram
0085d02c    0085d02c    00000004   00000000    rw- .tls_tp
0085d030    0085d030    00021fe0   0001fec0    rw-
0085d030    0085d030    0001fec0   0001fec0    rw- .localfar
0087cef0    0087cef0    00002000   00000000    rw- .stack
0087eef0    0087eef0    00000120   00000000    rw- .cio
0087f010    0087f010    00000018   00000018    r--
0087f010    0087f010    00000018   00000018    r-- .init_array
0087f028    0087f028    00000004   00000004    rw-
0087f028    0087f028    00000004   00000004    rw- .extdata

No matter what attemps I tried, the compiler seems to place .localfar always in L2.
The following line in the config file is completly ignored:

Program.sectMap[".localfar"] = "MSMCSRAM";

Does .localfar have to be located in L2, or are there any tricks to make the compiler place it in MSMCSRAM?

Thank you in advance, Clemens

over 12 years ago

0 Ajay Jayaraj over 12 years ago

TI__Expert 3350 points

Clemens Eisserer said:
Does .localfar have to be located in L2, or are there any tricks to make the compiler place it in MSMCSRAM?

localfar contains variables that must be local to each core and cannot be placed in MSMCSRAM.

Ajay

0 Clemens Eisserer over 12 years ago in reply to Ajay Jayaraj

Expert 2430 points

Sad to hear - those 128kb of local variables eat up a quarter of the 512kb available L2 memory.
Isn't there no way to allocate a seperate area for each core, as its done with the OpenMP stacks placed in DDR3 or MSM?

Thanks, Clemens

0 Ajay Jayaraj over 12 years ago in reply to Clemens Eisserer

TI__Expert 3350 points

Clemens Eisserer said:
Isn't there no way to allocate a seperate area for each core, as its done with the OpenMP stacks placed in DDR3 or MSM?

For OMP thread stacks, we can dynamically allocate the stacks and associate each stack with a thread. For the variables, the address cannot be dynamically determined because they need to be known at link time. We are exploring reducing the size of these sections, but I don't have a time frame for when those changes will be available.

Ajay

0 Clemens Eisserer over 12 years ago in reply to Ajay Jayaraj

Expert 2430 points

Hi Ajay,

Thanks for the detailed explanation. Looking forward to further improvements of the OMP runtime.

Regards, Clemens

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Howto place.localfar in MSM instead of L2?