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Posted Sep 24, 2007 13:52 UTC (Mon) by vapier (subscriber, #15768)
In reply to: banks? by sbishop
Parent article: What every programmer should know about memory, Part 1

unfortunately, the memory management in Linux is completely transparent to userspace which means the advantages of placing your data in different banks is totally not doable.

it's really only possible when you're writing your own bare-metal applications as then you have full control over the physical memory layout. your custom linker scripts would place the data such that you make sure specific pieces of data lie in specific banks.

of course, this is beyond the stated scope as it isnt Linux :)

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Posted Sep 24, 2007 16:54 UTC (Mon) by sbishop (guest, #33061) [Link]

Now you've got the Gentoo crowd double checking their linker man page... :)

Seriously, I've heard that the translation from a physical address to a particular bank/row/column combination is specific to the memory controller. Which makes perfect sense.

Also, let me make this clear: my bank comment was in regards to the "more details than you really need to know" section anyway. With Linux and/or random, commodity hardware, you can't call out a specific row or column either. But if you're going to talk about rows and columns, you ought to at least mention banks, the third address component of a modern DRAM. ("Modern DRAM" here means, approximately, anything I'm familiar with: Sync-DRAM, DDR, DDR2, etc.)


Posted Sep 24, 2007 20:18 UTC (Mon) by vapier (subscriber, #15768) [Link]

i might point out that linker scripts arent documented in the linker man page

i obviously cant read minds, but i think the discussion of being able to scan rows without re-issuing a CAS command will lead into the idea of accessing data in a certain fashion (in sequential lines) rather than much more randomly ... whereas with banks, exhibiting certain behavior at runtime wont matter since in general, being in different banks is random

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