[Pharo-project] Design change possible with fast SSD's possible?

Michael Haupt mhaupt at gmail.com
Sat Jan 14 15:55:51 CET 2012


Hi,

2012/1/14 Janko Mivšek <janko.mivsek at eranova.si>:
> Conclusion? Why RAM won't be just a L3 cache in a whole hiearchy of
> caching from SSD up to CPU? Automatic, supported by OS or even hardware,
> as CPU caches are? Then image wont be needed to be read to RAM and
> snapshoted back to disk, it can be run directly from disk.

SSDs are Flash memory. The number of write cycles is limited before
the memory starts to fail. Smalltalk frequently performs GC, which
involves moving objects, i.e., writing. Writing is also much slower
than reading, and AFAIK possible only block-wise (with a block being
significantly larger than your average object). Flash file systems
apply optimisations to distribute writing evenly, avoiding excessive
writing in some places and consequent earlier failure.

Best,

Michael



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