Re: Hibernation takes too long
> Afaik it's advised to copy files to SSDs and not copy blockwise (dd) because
> layouts can differ very much and performance would suffer.
As long as the filesystem is properly aligned on a 4KB boundary, I don't
think there'll be any noticeable difference. I highly doubt this
explains the 2 minutes needed to hibernate.
>>At idle, only 1.2 Gb of RAM is occupied, so not all the 12GB should be
>>moved to SSD.
>
> The 6 GB of RAM will be moved to the swap partition.
No, only the occupied part of the RAM, and not even all of it (the
parts that correspond to memory-mapped files (e.g. libraries and
executables)) won't, for example. So we're likely taking about less
than 1GB in this 1.2GB case.
> That's why swap needs to be >= RAM for hibernating.
Actually, this is neither necessary nor sufficient:
- the RAM can't be saved into the part of the swap already used, so the
rule should be "the unused part of the swap >= RAM" in order for the
rule to be sufficient.
- as mentioned about, not all the RAM needs to be saved to swap, and
furthermore, hibernation usually compresses the data before saving it
into the swap space, so it typically needs significantly less than the
RAM (I'd expect a compression in the order of 3x).
> The X61 will throttle SSD throughput as it has less bandwidth than modern
> SATA adapters. So, transferring those 6 GB
> will take time...
1GB/3 is about 300MB, which shouldn't take more than 10s to save.
Stefan
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