[maemo-developers] [maemo-developers] Adding swapon/off to Jakub's Load-Plugin applet

From: Dave Neuer dave.neuer at pobox.com
Date: Fri Feb 24 16:57:46 EET 2006
On 2/23/06, David D. Hagood <wowbagger at sktc.net> wrote:
> Koen Kooi wrote:
> > Please tell me I'm reading this wrong: 'swap file on the internal
> > flash'. You do know that flash is broken after ~100k writes/cell, right?
> > And you know that will break your 770, right?
> >
> >
> I think you are living in the past. Modern flash chips have a write
> endurance of greater than a million cycles. Also, wear leveling means
> that even if you repeatedly write to the same logical sector number a
> million times, you will NOT have written to any one flash location over
> a million times. Life cycle endurance is not a reason not to use
> internal flash as swap.
> Now, the fact that internal flash is a very limited resource and is not
> expandable, as is external flash - that is a reason not to use internal
> flash for swap.

Wear leveling on the internal flash depends on FS (i.e., software)
support, doesn't it? I wonder what the performance overhead of that
is, and also the stability of the swap + JFFS2 path vs. the swap +
swap partition path (of course, my ignorance of the swap code shows
here; my big assumption is that in the case of a swap partition, the
swap code goes straight from memory to blocks on a block device,
skipping the FS layer altogether).

Wear leveling on MMC is done by the hardware, isn't it? So we're
really talking about the difference between swapping to a file on a
JFFS2 fs on internal flash vs. swapping to a swap partition on MMC?

I really think for most people, the decision is really more of a
"commodity hardware" vs. "non-commodity hardware" one. I.e., can you
more afford to replace a non-standard part (the 770, or the internal
flash of the 770) or a standard part (mmc card) in the event that
something goes wrong.


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