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Linux on the Nokia 770 Internet Tablet (O'ReillyNet)Linux on the Nokia 770 Internet Tablet (O'ReillyNet)Posted Jul 22, 2006 20:16 UTC (Sat) by Los__D (guest, #15263)In reply to: Linux on the Nokia 770 Internet Tablet (O'ReillyNet) by jem Parent article: Linux on the Nokia 770 Internet Tablet (O'ReillyNet)
Now, I'm pretty sure they've done quite a bit of research before implementing this, but using the flash as swap does sound pretty evil to the FlashRAM itself... Do you know which techniques they use to avoid the flash being "spent" quickly?
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Linux on the Nokia 770 Internet Tablet (O'ReillyNet) Posted Jul 24, 2006 7:31 UTC (Mon) by dufkaf (subscriber, #10358) [Link] They are not swapping to internal flash but to MMC card. Modern cards should handle wear leveling by itself pretty well and if not you just buy new card next year :)
Also enabled swap is useful and the device feels faster even when it doesn't swap at all or just swaps away some unused garbage one time so in fact there are not much writes if used wisely. Heavy swapping makes the device slow/unusable anyway.
Linux on the Nokia 770 Internet Tablet (O'ReillyNet) Posted Jul 24, 2006 14:39 UTC (Mon) by jhoger (guest, #33302) [Link] Even with wear leveling a given sector only gets 100,000 erasures, typically.
But like you say at least it is external flash.
The OLPC project seems to be pursuing a swap-to-compressed RAM. In the right balance, this might help to make swap addicted applications perform OK. It remains to be seen though, since already compressed data in RAM won't get any benefit from this. Maybe mixed with swap to flash this would be a reasonable solution.
The best solution is for applications to not keep in RAM what they do not need. But that's a programmer bug, so, hard to fix.
-- John.
Linux on the Nokia 770 Internet Tablet (O'ReillyNet) Posted Jul 27, 2006 8:31 UTC (Thu) by ekj (guest, #1524) [Link] If you swap to a 1GB card, *constantly* with a rate of oh, say 5MB/s then you'll have written once to the entire card every 200 seconds.It'll take 200*100.000 seconds before you've written 100.000 times to any sector (assuming the wear-leveling routines are perfect, which ougth to be only a few percent away from true) That is a 250 days of 24*7*365 round-the-clock swapping. For most usage-scenarios, flash-wearout is a non-issue. These devices *wont* typically be used 365 days a year, 24 hours a day. More like 250 days a year, 3 hours a day. (even that is very heavy use, more than the average laptop sees) in which case the flash would survive 7.5 *years*. And even that assumes that it's *constantly* swapping at 5MB/s, which is obviously nonsense. I find it very unlikely that you'd ever manage to wear out a 1GB flash in any setting outside of round-the-clock stress-testing for several YEARS. And even if, buying a twice as large flash-chip will ensure it lasts twice as long.
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