[Techtalk] more cores, more slows

Tracey tclark77 at tlcnet.info
Tue Jun 19 18:10:09 UTC 2012


On 06/19/2012 12:44 PM, Carla Schroder wrote:
> It seems the more powerful hardware gets, the more software sucks it up, so it
> still feels like driving an old 486 SX.

This can be true, and certainly frustrating when your shiny new hardware 
runs like you remember the box you had years ago did. New & more bloated 
software can be to blame, but it isn't the only factor to consider.

>   My main PC has an AMD Phenom 8750
> triple-core processor with 4GB RAM, and a discrete Nvidia graphics card
> running the Nvidia driver. I use this machine for video, audio, and photo
> editing.  I thought that with three cores there would be less lag on all of
> these CPU-intensive tasks, and it is better than the old cheapie one-core
> CPUs, but I'm still feeling like it should be better.

For what it's worth, your hardware is more beefy overall than mine 
(although I have 2G more RAM). My machine isn't the fastest thing on a 
desk, but it's certainly not sluggish. Your feelings are a valid 
indication that *something* is slowing up the works. The next step is to 
get some measurable data on where the slowdown is coming from. The best 
thing is to then do a few simple tests to find out what exactly is 
causing the slowness.

One of the best resources for this is the command line tool "top". It 
will show you at the top of the list what's eating up the most CPU and 
RAM. It will also have a stat "wa" that indicates hard drive I/O wait. 
These three things will give you a really good idea of where the 
bottleneck is. If there's a bottleneck, the overall load average will 
increase. There are good articles that go into more depth about how to 
read the load averages, but as a general rule, the number should not 
exceed the number of cores. In your case, if your average load is going 
above 3 a lot, you know there's a bottleneck that needs to be addressed.

For and example of how this can help, Firefox is a known memory hog. If 
you leave it open for days on end, it takes up more & more memory. You 
can see this in top quite easily, Firefox will show something large in 
the %MEM column. If a program does this, a simple way to free up 
resources is to get in the habit of shutting it down at the end of the day.

Another thing I've seen happen on numerous servers is the disk "wa" 
percentage start getting really large when there are disk problems that 
aren't causing data loss (yet). Generally, if your wa% is above 1, there 
may be a problem. Consumer grade drives don't log much to the system 
logs until they start having catastrophic problems. If you see anything 
about your filesystem in the dmesg output or /var/log/messages (wherever 
that is on your system), the filesystem may be needing repair or the 
physical disk may be in trouble.

>
> The biggest offender is Web pages. Facebook is nasty, of course, with all of
> its squillion random scripts coded by gerbils on crack, and lots of other.

In applications, there are ways to curb resource usage. With the 
browser, addons such as Ad Block, Ghostery, No Script and FlashBlock 
will reduce the amount of junk websites load. This will especially help 
with pages like FaceBook. Once you find out what software is using the 
most resources, you can fine tune them from there.

Tracey C





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