Consequences of no swap

PlatinumX · 02-02-2009, 09:04 AM

Hi all,

I am running a small embedded system with a small HDD capacity.
However, RAM is 512 MB, which seems a lot compared to the applications running on it.

I am wondering of removing swap parition or file, to have more free space on the tiny HDD.

Did somebody try running without swap already ?
What happens if there is not enough physical RAM space ?

Thanks

r3sistance · 02-02-2009, 09:19 AM

Generally the results of not having enough memory are things gridding to a near halt or even crashing. But it takes alot to really cause that effect. I believe if their is no swap, some distributions may use a section of / as swap (similarily to windows and virtual memory out of C:) but not certain of that. Generally it'd be wise to have 1GB of dedicated swap on that system. When you are talking a small capacity HDD, how small and what's it running?

metrofox · 02-02-2009, 09:27 AM

Quote:

Did somebody try running without swap already ?

I tried once and nothing happened, but my RAM is 1 Gb.

Quote:

What happens if there is not enough physical RAM space ?

Your PC will crash or will get slow.

In the end...How large is your swap? 1 Gb, 512 Mb? What do you recover with one 1 gb. or 512 Mb...You may have complications...

pixellany · 02-02-2009, 09:32 AM

I assume that the behavior when running out of memory will be very different depending on what SW you are running. There are typically a number of calls to allocate memory, and then a decision as to what to do if the request is not successful.

I can't think of any way to definitively answer your question except by running tests.

I've never heard of a distro "using /" for swap space but, regardless, this would still use disk space.

r3sistance · 02-02-2009, 09:34 AM

I could have been wrong about /

. I dunno that much about the indepths of linux, however on such a low speced system, if it's important I wouldn't be able to sleep at night if it didn't have a proper defined swap.

metrofox · 02-02-2009, 09:37 AM

Any way...I do not need of a swap...My swap uses the 1% of its resources...

To PlatinumX: How many resources your swap uses?(I think higher than mine)...

PlatinumX · 02-02-2009, 09:49 AM

Quote:

To PlatinumX: How many resources your swap uses?(I think higher than mine)...

I don't have a the precise answer here.
I will check this.

Thanks for info guys

r3sistance · 02-02-2009, 11:37 AM

Just use the top command in bash or a ssh shell and it will tell you. It's q to quit for top.

metrofox · 02-02-2009, 12:02 PM

Code:

Swap:  2096440k total,        0k used,  2096440k free,   420832k cached

That's what my swap says...As you can see my swap doesn't consume resources, 0k used...I don't know why I gave 2 Gb to swap when it needs 1Gb at max.(next installation I'll remove it

)...Maybe I had in my head that swap had to be double than RAM, but that technical worked for 2.4.x kernels...