Q about swap size

JD jd1008 at gmail.com
Sun Jul 11 19:51:36 UTC 2010


  On 07/11/2010 12:29 PM, JB wrote:
> JB<jurek.bajor<at>  gmail.com>  writes:
>
>> ...
>> top - 10:43:15 up 2 days, 6 min,  5 users,  load average: 8.62, 6.84, 6.26
>> Tasks: 244 total,   7 running, 237 sleeping,   0 stopped,   0 zombie
>> Cpu(s): 60.7%us, 23.5%sy,  9.2%ni,  0.0%id,  0.0%wa,  5.4%hi,  1.3%si,  0.0%st
>> Mem:    509800k total,   502624k used,     7176k free,    16280k buffers
>> Swap:  1048568k total,   317372k used,   731196k free,   101944k cached
>>
>>
>> This indicates only about 30% of my 1GB swap is being used. Would increasing
> that to 2GB have any affect on the load average performance?--Doc Savage
> Fairview Heights, IL
> Hi,
> Please disregard my previous message - it has some typos (high temps here :) ).
>
> Would you please take a look at 'top' output (Ctl-M - sorted by memory use)
> and share with us the system lines plus following 10 lines. Note that
> the display may fluctuate, so wait for a while to understand what is really
> happening and then capture the output for us.
>
> As a general rule, your min swap size should be:
> RAM size plus 20%
> This is due to "save to swap" requirement for hibernation.
> JB
>
>
>
>
>
But for running many apps that use a large dataset, you want at least 2X 
physical ram of swap space -
albeit, running such a huge app on systems that are starved for PHYSICAL 
RAM can lead to extremely poor
performance at the least - and the system with thrash from excessive 
page-in's and page-out's and full tilt
swap-in's and swap-out's. AT the worst, the system will lock up.



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