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Un-met Expectations -- a real example

Posted 11-03-2010 at 07:24 PM by SaintDanBert

It seems that suspend-to-ram ("suspend" or "sleep") and suspend-to-disk ("hibernate") requires that the workstation get installed with a swap partition -- not file, partition.

Moreover, the partition must meet size requirements. Specifically, the partition size must be base plus lagnaippe. The base must be at least as large as the physical ram installed in the workstation.
The lagnaippe is a little extra swap space in case any of the swap space is actually in use at the time one requests either suspend. Recently, Canonical Support suggested a 4.5 GB swap partition for a workstation with two 2GB ram sticks installed.

Workstations with large amounts of physical ram will likely refrain from much in the way of routine swapping.
Programming tricks like "cathedral windows" for file access might use swap space in other ways. Only your applications know what they are doing and so your need for lagnaippe swap space is specific to your system use.

There is another skid mark on this topic. That is the issue of 32-bit vs. 64-bit vs. physical memory. As I understand things, 4 Gbytes of ram is 2**32 bytes. In contrast a 32-bit address space can access 2**32-1 bytes -- one less -- physical bytes. Therefore, a 32-bit distro release requires the physical address extension (PAE) kernel package to access all of the 4 Gbytes of physical ram. This applies not only to the running kernel but also
to the boot loader. A 64-bit distro release does not have these limits. Your mileage may vary.

-- Saint DanBert
________________________________
"lagnaippe" (pronounced "lan-yapp" in New Orleans, LA USA) means "a little extra". The 13th doughnut in a baker's dozen is "lagnaippe."
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  1. Old Comment
    Quote:
    There is another skid mark on this topic. That is the issue of 32-bit vs. 64-bit vs. physical memory. As I understand things, 4 Gbytes of ram is 2**32 bytes. In contrast a 32-bit address space can access 2**32-1 bytes -- one less -- physical bytes. Therefore, a 32-bit distro release requires the physical address extension (PAE) kernel package to access all of the 4 Gbytes of physical ram. This applies not only to the running kernel but also
    to the boot loader. A 64-bit distro release does not have these limits. Your mileage may vary.
    Not exactly. 4 Gbytes of ram is 2**32 bytes and a 32-bit address space can access exactly 2**32 bytes (0 through 2**32-1 bytes inclusive). BUT, the motherboard BIOS will want some of that 32-bit address space (typically the last gigabyte) for its hardware, leaving only 3 Gbytes or so for actual addressable ram in the 32-bit address space. Any ram beyond that amount, the motherboard will bump up beyond the 32-bit address space. Therefore, if you have 4 Gbytes of physical ram, you will need to use PAE in the kernel in order to be able to see all 4 Gbytes of ram. Otherwise, you will only see the 3 Gbytes or so that the motherboard allows in the 32-bit address space. PAE is clever hand waving in the microprocessor paging module that essentially allows the microprocessor to generate a 36-bit address (64 Gbytes addressable) from the 32-bit address it is given. A 64-bit distro release does not have these limits, since it uses long mode in the microprocessor chip and that uses a 64-bit address space (17179869184 Gbytes addressable).
    Posted 08-04-2014 at 03:08 AM by xode xode is offline
 

  



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