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Re: Hibernation takes too long

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What is the proportional size between RAM and swap?


On Sun, 2019-07-21 at 10:19 -0400, Stefan Monnier wrote:
> > 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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Thread

Hibernation takes too long Shahryar Afifi <shahryarafifi@yahoo.com> - 2019-07-20 06:50 +0200
  Re: Hibernation takes too long Carl Fink <carlf@panix.com> - 2019-07-20 15:30 +0200
    Re: Hibernation takes too long Shahryar Afifi <shahryarafifi@yahoo.com> - 2019-07-20 17:20 +0200
      Re: Hibernation takes too long Rick Thomas <rbthomas@pobox.com> - 2019-07-21 02:20 +0200
        Re: Hibernation takes too long Shahryar Afifi <shahryarafifi@yahoo.com> - 2019-07-21 02:50 +0200
          Re: Hibernation takes too long Michael Kesper <mkesper@schokokeks.org> - 2019-07-21 05:00 +0200
            Re: Hibernation takes too long Stefan Monnier <monnier@iro.umontreal.ca> - 2019-07-21 16:20 +0200
              Re: Hibernation takes too long Shahryar Afifi <shahryarafifi@yahoo.com> - 2019-07-21 16:40 +0200
                Re: Hibernation takes too long Stefan Monnier <monnier@iro.umontreal.ca> - 2019-07-21 18:50 +0200
            Re: Hibernation takes too long Anders Andersson <pipatron@gmail.com> - 2019-07-21 20:10 +0200
              Re: Hibernation takes too long Stefan Monnier <monnier@iro.umontreal.ca> - 2019-07-22 16:00 +0200
              Re: Hibernation takes too long Rick Thomas <rbthomas@pobox.com> - 2019-07-23 10:30 +0200
        Re: Hibernation takes too long Carl Fink <carlf@panix.com> - 2019-07-21 04:10 +0200
  [Solved] [Fwd: Hibernation takes too long] Shahryar Afifi <shahryarafifi@yahoo.com> - 2019-07-30 17:50 +0200

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