BBS:      TELESC.NET.BR
Assunto:  Re: Adding a hardware swap partition
De:       Theo
Data:     Fri, 13 Mar 2026 18:28:05 +0000
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The Natural Philosopher  wrote:
> On 13/03/2026 14:16, Theo wrote:
> > The Natural Philosopher  wrote:
> >> I think that is an interesting summary, the point being made that speed
> >> is dominated today by disk access times, not CPU cycles in addressing  a
> >> file system.
> >> And with the demise of spinning rust, there is no seek delay either, so
> >> the theoretical advantages of an actual partition in the disks low
> >> sector area, no longer outweigh the operational simplicity of a swap file.
> >>
> >> Like so many other things that grew out of limited RAM and slow spinning
> >> rust disks, the swap partition is really no longer necessary...
> > 
> > One advantage of a swap partition is that it's a dedicated space - if you
> > start running low on space it may limit the size of swapfile that can be
> > created, which has a knock-on impact on performance.
> > 
> I dont think you understand the nature of a swapfile.
> 
> It is a fixed length file.

Ah, it seems only Windows does variable length files.

Depending on the filesystem the swapfile may not be backed by physical
blocks, ie the file exists but the space is not preallocated.  It looks like
you have to explicitly force that.

> > Another reason is if you're using hibernate.  You need swap space at least
> > as large as RAM to save out your memory contents to, so that can prevent
> > hibernate working if you are running low on space.  Also hibernate/restore
> > is a fairly low-level process and swap partitions are easier to setup for
> > that than swap files.
> > 
> Again, you are talking bollocks. Swap files are pre-allocated, of fixed 
> size, and zero filled.

For swap files, hibernation appears to be more complicated:

https://wiki.debian.org/Hibernation/Hibernate_Without_Swap_Partition

indicates you need to tell the kernel the offset of the swapfile within the
partition, which suggests that the kernel is reading it directly rather than
via the filesystem.  That implies the filesystem must allocate it
contiguously and is not allowed to have any kind of fragmentation.  That
means it could be impossible to set up on a machine that's been running a
while.

Theo

--- PyGate Linux v1.5.13
 * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

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