Re: Query about existence of way to free up unnecessary RAM usage
On 10/09/2014, Steve Litt <slitt@troubleshooters.com> wrote:
> On Wed, 10 Sep 2014 16:04:46 +0800
> Bret Busby <bret.busby@gmail.com> wrote:
>
>> On 10/09/2014, Steve Litt <slitt@troubleshooters.com> wrote:
>> > On Tue, 9 Sep 2014 21:51:35 +0200
>> > Bzzzz <lazyvirus@gmx.com> wrote:
>> >
>> >> On Wed, 10 Sep 2014 03:30:40 +0800
>> >> Bret Busby <bret.busby@gmail.com> wrote:
>> >>
>> >> > Alright, then; it is doing token swapping - with 99% of 16GB
>> >> > memory usage, and, swapping only 4% of (about) 40GB swap
>> >> > capacity, you can't seriously tell me that the swapping is
>> >> > working as it should be.
>> >>
>> >> Anyway, a swap of 40GB is too much for a RAM of 16GB (should be
>> >> around 16-20GB), unless you perform operations that generates
>> >> a lot of intermediary results).
>> >
>> > The reason I agree with you is that if you need to swap anywhere
>> > near 40GB of swap, your computer will be crawling to the point
>> > where you might as well abort the guilty program (if you can
>> > navigate to do so), or reboot the compute.
>> >
>> > That said, I just found out my swap partition is 44GB for a 16GB
>> > semiconductor RAM.
>> >
>>
>> So, does swapping work on your system?
>>
>> Does your RAM usage go above 50%, without swapping, and, above 90%,
>> with less than 5% of the swap capacity being used?
>
> Hi Bret,
>
> I can't answer your question in English, because I've never really
> understood Linux memory usage. There's an algorithm to figure out how
> much RAM to use in order to cache disk accesses, and another algorithm
> to figure out how much swap partition to use to substitute for RAM, and
> it just twirls my head.
>
> So the best thing I can do is show the results of a couple commands:
>
> slitt@mydesq2:~$ vmstat -SM
> procs -----------memory---------- ---swap-- -----io----
> r b swpd free buff cache si so bi bo
> 0 0 0 7113 682 5172 0 0 14 20
> slitt@mydesq2:~$ free -h
> total used free shared buffers cached
> Mem: 14G 8.0G 6.9G 0B 682M 5.1G
> -/+ buffers/cache: 2.2G 12G
> Swap: 44G 0B 44G
Hello.
I believe that, whilst you did not state the answer, the answer is
shown, in part, above.
With my limited understanding, what I deduce from the output of the
free -h command above, is that your system is shown as having 14GB (?)
of RAM, and, at the time of the command being run, 8GB of that (almost
60%, for 14GB, or, half, for 16GB) is being used, and, at that rate of
usage of the RAM, no swapping is occurring.
What output do you get for the free -h command, when >=90% of your RAM
is being used?
And, what is your swappiness setting?
I am putting these questions to youu, as you seem to have the same (or
similar) RAM and swap capacities, as my desktop system, that is this
system that I am using, in which I have the problem with the lack of
swapping.
At present, I have
"
bret@bret-dd-workstation:~$ free -h
free: invalid option -- 'h'
usage: free [-b|-k|-m|-g] [-l] [-o] [-t] [-s delay] [-c count] [-V]
-b,-k,-m,-g show output in bytes, KB, MB, or GB
-l show detailed low and high memory statistics
-o use old format (no -/+buffers/cache line)
-t display total for RAM + swap
-s update every [delay] seconds
-c update [count] times
-V display version information and exit
bret@bret-dd-workstation:~$ free -g
total used free shared buffers cached
Mem: 15 14 0 0 0 1
-/+ buffers/cache: 12 2
Swap: 40 1 39
"
--
Bret Busby
Armadale
West Australia
..............
"So once you do know what the question actually is,
you'll know what the answer means."
- Deep Thought,
Chapter 28 of Book 1 of
"The Hitchhiker's Guide to the Galaxy:
A Trilogy In Four Parts",
written by Douglas Adams,
published by Pan Books, 1992
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