Why is swap being used?

Crisis · l33t Joined: 10 Feb 2003 Posts: 613 Location: Portland, OR

Seems I keep swapping out space even though mem is free:

Anime_Fan · Posted: Fri Apr 16, 2004 8:02 pm Post subject:

Used memory isn't freed.
You probablt were using more memory than your RAM could handle at one point. Thus, it will say that you use(d) swap.

Crisis · l33t Joined: 10 Feb 2003 Posts: 613 Location: Portland, OR

Is there any way to see the current swap usage?

Also, why would memory show as 89 instead of the 96 I have?

Thanks!

Nate_S · Guru Joined: 18 Mar 2004 Posts: 414

the mem amount thing I think is the difference between "salesman's megs" and real megs showing up, 1000 vs 2^10=1024

I'd also like to know if you can see current swap usage.

sapphirecat · Guru Joined: 15 Jan 2003 Posts: 376

speed_bump · Posted: Sat Apr 17, 2004 1:57 pm Post subject:

Another possible reason for seeing 89 megs instead of 96 may be that your video card is "sharing" memory with the system. That is, instead of having its own physical memory, the video card is using some of your system's memory. Your BIOS should tell you if that's the case.

Souperman · Posted: Sun Apr 18, 2004 9:23 am Post subject:

The "lost" memory is used by the kernel. As you can see, mine show 503 total instead of 512. I don't have onboard VGA which could share memory.

speed_bump · Posted: Sun Apr 18, 2004 5:19 pm Post subject:

Another thing to be aware of (getting back to the original question) is that the kernel will try to keep a certain percentage of RAM free in order to mitigate possible thrashing and deadlock scenarios. So in small memory configurations, it's very possible to have swap used even though there is RAM available.

In general, the kernel will try to move pages to swap that have not been used recently so this isn't a big deal. However, "recently" is an vague term and on a very busy system "recently" might be on the order of seconds rather than minutes or hours.

Is this causing you problems?