[GTALUG] optimum swap size

[David Collier-Brown]

Well. sorta /proc, that underlies most Linux tools --dave


On 2019-02-27 4:48 p.m., Gary via talk wrote:
> I suspect you use vmstat to determine the swap usage (?)
> /gary
>
> On 19-02-27 01:14 PM, Dave Collier-Brown via talk wrote:
>>
>> Linux is somewhat unusual in that it dynamically kills large 
>> processes when it's running out of memory. You used to have to set 
>> limits to get that behavior.   Because of it, I run a moderately 
>> large swap (~8 GB) and can watch large jobs drive swap usage up. Then 
>> /*I*/ decide if I want them dead.
>>
>> --dave
>>
>> On 2019-02-27 10:38 a.m., Stewart C. Russell via talk wrote:
>>> On 2019-02-27 10:02 a.m., Gary via talk wrote:
>>>> I have kubuntu 18.04 with 20 gigs ram. Does anyone know what the optimum
>>>> size swap area that I should have?
>>> I asked a question about this at a GTALUG Q&A a few years back.
>>> Basically what I remember was:
>>>
>>> * are you frequently running out of memory? If not, don't change anything.
>>>
>>> * depending on what applications you're running, there are various
>>> kernel parameters that govern swap behaviour. They're tuned for
>>> "typical" performance.
>>>
>>> * The OOM killer (out-of-memory process killer) can sometimes kill a
>>> task that's taking up what it thinks is too much memory. I sometimes get
>>> that with very large (or very badly thought out) OpenSCAD renders, and
>>> it can be annoying to have to work round it. OOM killer exists to keep
>>> the system stable, and doesn't care if your work isn't happening.
>>>
>>> Swap is more of a thing on smaller machines such as a Raspberry Pi.
>>> These days, you've always got enough memory + swap until you find that
>>> one job for which you don't. For me, that was trying to build MySQL (for
>>> someone else, I promise!) on a Raspberry Pi.
>>>
>>> cheers,
>>>   Stewart
>>>
>>>
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>> -- 
>> David Collier-Brown,         | Always do right. This will gratify
>> System Programmer and Author | some people and astonish the rest
>> dave.collier-brown at indexexchange.com  |              -- Mark Twain
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-- 
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
davecb at spamcop.net           |                      -- Mark Twain

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