New i5-3550 PCs slow, disk cache usage high

Hi, I just bought a few Dell Optiplex 7010s desktop PCs (“new PCs”) with Intel i5-3550 processors, and installed OpenSuse 12.1 on them. My problem is that they are performing very badly, as if I were using classic Pentiums. For example, using the KDE desktop, practically everything in these new PCs is painfully slow/laggy/jerky: opening/closing applications, mouse actions, keyboard input, to name a few. I am in particular comparing their performance to a couple of Dell Optiplex 390s (“old PCs”) I have that are equipped with the slightly slower i5-2400 processors. I have had no problems with the i5-2400s since I set them up – very smooth, very fast. All my PCs have 4GB physical memory, 4GB swap, and have practically the same set of programs installed. I decided to check the memory usage of freshly rebooted PCs, and found that the new PCs have only 20% free physical memory, as the disk cache is using 61% of the 4GB total physical memory. The old PCs on the other hand have 78% free physical memory, as only 10% is being used by the disk cache. This substantial difference in memory usage might be a symptom of the problem. Any thoughts on what the problem might be in my new PCs, and how can I fix this? Is my OS perhaps not recognizing these new processors, and hence I should install some additional drivers?

I know nothing of Intel processors as I only use AMD; however, if you want lots
of free memory, you are using the wrong OS. Windows tries to keep as much memory
free as possible, while Linux operates from the philosophy that unused memory is
wasted. The OS can release disk cache very quickly when it is needed for other
purposes. Meanwhile, access to files is greatly improved by having as large a
cache as possible. The system with 78% free memory is the one that seems wrong
to me. My box with 3 GB RAM has 130724 bytes free with 50% of RAM in the cache.

As the i5-3550 likely was released later than kernel 3.1 that is found in
openSUSE 12.1, it is possible that your kernel does not recognize it. I suggest
that you might try kernel 3.4 or 3.5, either by building your own, by getting
one from one of the kernel repositories, or by booting a 12.2 RC1 Live CD.

Thanks for the suggestion. I think I’ll try my luck with building openSUSE with an updated kernel. Do you know exactly which kernel version OpenSUSE 12.2 RC1 is using, and which kernel version the (mid-September?) release version of 12.2 will be using?

I only know the current kernel in factory is 3.4.4. software.opensuse.org:

On 07/24/2012 11:00 AM, Larry Finger wrote:
> I know nothing of Intel processors as I only use AMD; however, if you want lots
> of free memory, you are using the wrong OS. Windows tries to keep as much memory
> free as possible, while Linux operates from the philosophy that unused memory is
> wasted. The OS can release disk cache very quickly when it is needed for other
> purposes. Meanwhile, access to files is greatly improved by having as large a
> cache as possible. The system with 78% free memory is the one that seems wrong
> to me. My box with 3 GB RAM has 130724 bytes free with 50% of RAM in the cache.

Old timer here… I remember things a bit differently. Back in the mid 90’s, it
was NTFS that was spanking our hiney by using extreme caching on the disk.
Later, Linux did similar tricks. Somebody can correct me if I’m wrong. I’m
talking about the 2.0 era approximately.

Using cache is usually a good thing… so as this poster mentions, nothing to
worry about. The “free” command shows you your memory without the caching…
and you don’t need to view the cache as “overhead”.

>
> As the i5-3550 likely was released later than kernel 3.1 that is found in
> openSUSE 12.1, it is possible that your kernel does not recognize it. I suggest
> that you might try kernel 3.4 or 3.5, either by building your own, by getting
> one from one of the kernel repositories, or by booting a 12.2 RC1 Live CD.
>

My guess (to the OP), and it’s just a guess is that the “slowness” may have much
to do with the Ivy Bridge GPU handling (?). And yes, a newer kernel may
actually help this. With that said, the i5-3550 comes with the slow HD 2500
graphics. Just saying…I don’t think that means “jerkiness” is deserved,
shouldn’t be that bad… but don’t expect wonders from the integrated GPU.

Problem solved! I decided not to rebuild OpenSUSE 12.1 but simply upgrade the kernel to version 3.4.5 (for details see http://forums.opensuse.org/forums/english/get-technical-help-here/install-boot-login/476981-opensuse-12-1-kernel-upgrade-install-details-needed.html) and now everything is fast, smooth. Thanks for the inputs everyone.