On Fri, 10 Aug 2007 23:16:45 +0200, roland said: > http://pdos.csail.mit.edu/papers/softecc:ddopson-meng/softecc_ddopson-meng.pdf > > "SoftECC : A System for Software Memory Integrity Checking" > > Is it possible to implement something like this within the Linux virtual > memory subsystem ? Anything that can be simulated with a Turing machine is *possible*. The question is how many rocket boosters the pig needs for takeoff. Hint: The thesis talks about why he didn't implement it for Linux. > If it can be done, wouldn`t this be a great feature ? Read section 5.2 of that thesis, particularly this quote from 5.2.2: "For random word writes, this implies that SoftECC will need an order of magnitude more compute time than the user-mode code" Basically, on every single memory page that gets dirtied, we have to then re-checksum the page (blowing away cache lines in the process). If you want to get a feel for it, find the kernel code that recognizes that a page is dirtied, and just add a few lines there: int foo = 0, i; for (i=0;i++;<1024) { // adjust for non-4K pages foo ^= *(page+i); } and see how much your system crawls. Personally, I'd recommend just shelling out the bucks for hardware ECC if the reliability matters.
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