To swap or not to swap ;-) (was RE: To lvm or not to lvm)

[Michael Butash]

I've run without swap while having 32gb of ram prior, and found things
would just be weirdly lagging at times without it.  Adding a swap partition
removed that, never really found out why.  Now I just always add a small
swap slice (usually 3-4gb) even if setting swappiness to minimum.

I never do suspend/hibernate or anything to swap, as I often have big
enough ram that it chewing into ssd space for it wasn't an option.  I just
sleep the laptops, and my desktops are never really powered down to bother
either.

-mb

On Sat, Sep 22, 2018 at 8:25 AM Bob Elzer <bob.elzer at gmail.com> wrote:

> > 4 - not having swap seems to make some things not work too well
>
> Swap depends on how much memory you have and how much memory your programs
> need.
>
> Back in the day when ram was less than a gig we would use 2 to 3 times the
> ram size for swap. You would add up the number and size of your programs
> you needed to run and give it that extra swap knowing that when swapping
> started it would slow things down some.
>
> Nowadays you can have 32, 64, 128gb and more ram.
>
> Programs are also bigger, but you still figure how much memory the
> programs take and add them all up and compare that with your actual ram.
>
> If you have 32gb of ram and only read mail and only browse google and
> PLUG, then you wouldn't really need any swap. But if you keep hundreds of
> tabs open, and have a huge memory resident database, and edit images and
> video, you may want to have swap.
>
> If you have 4-8gb of ram I would think 3 to 4 times that for swap.
> 16gb ram 1 to 2 times swap.
> 32 or more 1 times, depending on what you're doing maybe more.
>
>
>
> On Fri, Sep 21, 2018, 1:08 PM Carruth, Rusty <Rusty.Carruth at smartm.com>
> wrote:
>
>> So, in my limited experience with swapping, here's my conclusions:
>>
>> 1 - one big (that is to say, at least your ram size, and possibly 2x your
>> ram size) swap PARTITION is needed if you want to hibernate or suspend, and
>> I think it has to be the first one in your fstab (but I'm not sure on that)
>>
>> 2 - swap files work fine, but can't be used for suspend/hibernate.
>>
>> 3 - suspend/hibernate doesn't work with multiple partitions if (the first
>> one I think) isn't big enough to hold everything, even if the total swap
>> space is plenty big.
>>
>> 4 - not having swap seems to make some things not work too well, even
>> when you're not overflowing in to swap.  This one I don't have proof for,
>> but it just felt like a no-swap system ran in to walls sooner.
>>
>>
>>
>>
>>
>> -----Original Message-----
>> From: PLUG-discuss [mailto:plug-discuss-bounces at lists.phxlinux.org] On
>> Behalf Of Matt Graham
>> Sent: Friday, September 21, 2018 9:35 AM
>> To: Main PLUG discussion list
>> Subject: Re: To lvm or not to lvm
>>
>> ....  You might even be able to get away without swap if you don't want
>> to do suspend-to-disk.
>>
>>
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