Rowhammer mitigation

[cowbutt]

It is a bit confusing for me that you mix "reduce refresh interval" with "reduce refresh rate".

The mitigation is to reduce the refresh interval, that is, increase the refresh rate, right?

Yes, exactly so.

[cowbutt]

I've just come across http://www.thirdio.com/rowhammer.pdf which seems to reference this thread.

[traktorkontrol]

The standard recommendation is to reduce the refresh interval to 3.9ms and thereby double the refresh rate (source: http://support.lenovo.com/us/en/prod...ity/row_hammer). Doing that gave me one error per pass at the same address both times, so I reduced the interval to 75% of 3.9ms (i.e. tREFI=3510, tREFIX9=31) and it's now error free over 8 passes overnight.


Because the memory controller is refreshing slightly more frequently, it reduces the frequency which the RAM can be accessed, so it slightly hurts performance, but I don't care too much. 45GB/s is enough for me.

Hi CowButt, thanks for sharing that information, i followed your guide to change my BIOS parameters to double de refresh rate. But i want to ask you a technical question:

By doubling the refresh rate, do the memory will suffer long term side effects of performance degradation? I mean, it is a nice and elegant solution what you propose and what most venders implemented through patches, but, may it affect the memory in the long term?

Thank you.

[cowbutt]

By doubling the refresh rate, do the memory will suffer long term side effects of performance degradation?

With adequately-cooled hardware, I don't see how changing the refresh frequency will significantly affect the longevity of your memory modules.