Swap (and low memory) performance

[whatthefunk]

Before you do that fresh install (or during) you should make swap bigger if you can.

[SecretCode]

Thanks guys - I'm concluding that it's at least possible for swap to be used without a killer impact on performance. Time for a fresh install ...

[claydoh]

Hmm I lost a fairly long post here , for me anyway. I'd blame it on tapatalk but I know better

I have a Dell D630, dual core 2gb ram. Sometime in the past year or so, I have had a serious slowdown when the system goes to swap, seemingly before it needs to, and very often. I chalked it up to not enough ram, nepomuk/soprano, chrome, flash, an aged had drive, all the usual suspects. Try running the Gimp with Kontact and a few chrome tabs open and the countdown to uselessness is usually short. Turning stuff off, closing programs down, changing swappiness, etc only prolongs the inevitable if doing something Gimpy or tabby. I just can't pinpoint exactly when or which version I noticed this, but it was not originally like this.10.10 was the earliest release this machine would have seen.

Now my dell is waiting for some surgery, I am using the 2003 Compaq running Lubuntu (lxde) 12.04. I definitely has many fewer services running, however it has only 1gig ram, is a single core, yet I can run chromium and gimp without hitting swap so hard, fast, and furious as I near the limits of available memory.

[vinnywright]

IDK ...my box routinely uses swap to no ill effect ,,,,even right now doing nothing all day (just waiting for me to get home)

vinny@Vinnys-HP-G62:~$ free
total used free shared buffers cached
Mem: 3844396 2997080 847316 0 211656 1776436
-/+ buffers/cache: 1008988 2835408
Swap: 4096536 21364 4075172

I see this ,but the swap use was probable from watching video last night .

I can be recoding video(making DVD's) browsing the web,listening to music or vid's and DLing torrent's with swap being used and see no lag or bad performance hits.

all with 4Gig's RAM and 4Gig's swap (the swap NEVER gets all used) BUT the RAM will get used up almost all the way but some is always kept free.

VINNY

[oshunluvr]

I also think the new generation of SSD's are more stable. My very first SSD (a 32GB cheapo) died after six weeks. The warranty replacement is still running solid after two+ years. Assuming you buy a name brand with good reviews and support (like regular firmware updates) I think you can treat them as you would any hard drive...

...except you won't be waiting for it much!

[SteveRiley]

but the need for "wear levelling" technology certainly made good copy for the tech journalists and thus may have perpetuated fears for longer than is necessary.

And now that we have file systems supporting TRIM and vastly improved controllers, all those lagacy arguments are history.

[vw72]

I'm on 11.10 (KDE 4.7.4). I suppose I ought to get on and install 12.04 ... I've been meaning to for months but have been busy.

When I was having sporadic wait times in KDE, it was also on 4.7.x. I would seriously consider upgrading to see if the problem still exists.

[dibl]

The most swap space I ever needed was 15GB, on this machine which has 6GB of memory, and that was due to an unusual (for me) project, in which I used gimp to convert some 200+ .gif images into a motion .gif "video". Normal use, even with a single Win 7 VM running, rarely runs it above 1.9 or 2 GB of memory being used, and zero swap. I can run two VMs, plus normal packages and a browser, and not go into swap.However, running more than 2 VMs simultaneously will indeed force it into swap. And because a VM is a "running system", it is a different proposition than paging out part of a spreadsheet or some web pages or something static like that. That may be the explanation for the lousy performance when swap is being used by a system running multiple VMs.

[SecretCode]

Out of curiosity, what version of KDE are you using?

I'm on 11.10 (KDE 4.7.4). I suppose I ought to get on and install 12.04 ... I've been meaning to for months but have been busy.

[SecretCode]

I dont know if Id go the SSD route here. I love my SSD, but its not designed to be ram and constantly swapping on it will reduce the lifespan of it drastically. I have swap on my HHD. I think the only thing to do here is buy more ram.

I have read similar comments to this one in the past and I can't for the life of me figure out why people think this way. Maybe someone could enlighten me as to why this idea persists?

In the early days of SSDs there was a much more significant impact on lifecycle. Whether or not those early days overlapped with the advent of SSDs cheap enough for average users to consider replacing HDDs with them I don't know, but the need for "wear levelling" technology certainly made good copy for the tech journalists and thus may have perpetuated fears for longer than is necessary.

[vw72]

Out of curiosity, what version of KDE are you using? I ask, because I have had the problem you have described in the past and it had nothing to do with swap, but a faulty widget or service (I can't quite remember) You could try creating a new user with a default setup and see if the problem still exists.

[oshunluvr]

I dont know if Id go the SSD route here. I love my SSD, but its not designed to be ram and constantly swapping on it will reduce the lifespan of it drastically. I have swap on my HHD. I think the only thing to do here is buy more ram.

I have read similar comments to this one in the past and I can't for the life of me figure out why people think this way. Maybe someone could enlighten me as to why this idea persists?

My thoughts:
1. A computer with 4GB of ram is unlikely to be constantly swapping out to ram.
2. Even swapping several times an hour is nothing over the life-cycle of an SSD.
3. A consumer grade SSD has exactly the same warranty as a hard drive - three years.
4. Windows users use SSD's with a swap file that is used way more often than linux user's would be but I don't hear about wildly reduced SSD life-cycles for windows users.
5. SSD manufacturers do not prohibit or even recommend against using an SSD for swap files/partitions.
6. Hard drive manufacturers are using SSD's as cache for hard drives - which is exactly like swapping memory so they must be up for the job.
7. The increased performance-per-dollar of an SSD has to be the best bang for the buck in the computer world right now.
8. Why would you bother to upgrade to an SSD and then not use it precisely when it will make the most difference?
9. An SSD will be portable. That is to say - easily used on your next computer. However RAM - especially laptop sodimm is very unlikely to be usable on your next computer. A dying laptop is the last place to be putting your computer bucks into unless you have a large cache (is the pun too obvious? ) of money.

There are of course totally subjective opinions - I've done no real studies.

[whatthefunk]

I dont know if Id go the SSD route here. I love my SSD, but its not designed to be ram and constantly swapping on it will reduce the lifespan of it drastically. I have swap on my HHD. I think the only thing to do here is buy more ram.

[HalationEffect]

This is a subject that's still close to my heart... up until quite recently I was using a 10 year old PC with 1GB RAM, and a slow 40GB PATA HDD which was the boot drive and also where the swap partition lived. As you might imagine, even after installing the "low fat settings", I was in swap hell a lot of the time.

That's why when I finally scraped together enough cash to get a new machine, I spec'd it with 2 x 4GB RAM modules and an SSD (in addition to a 750GB SATA HDD for the /home partition to live on). Best decision I've made in a while

[ronw]

I went up to 8GB and never looked back

Thoroughly agree with this. When I ordered my current laptop, I decided to give myself a present and go with 8GB instead of 4GB. Talk about bang for the buck.