On 2012-11-20 Gilbert E. Detillieux wrote:
I wouldn't be so sure about that, unless you've really checked that closely, and/or disabled most system services that might affect
I have tried to monitor things closely with top, especially sorted by memory usage. I'm doubtful it's a change in usage that is causing this because I have such a big (5GB) usual buffer/cached/free area, and I really am doing nothing during these tests that would chew through 5GB of files or data. For instance, my cached line in top stays roughly the same. That would mean that it would have to be 4GB+ of other files being read to flush out the stuff I want cached.
I run a lot of services but I've disabled all "automatic" and "desktop" stuff, for instance I run no desktop index program, or anything like that.
It used to be that the only thing that would "uncache" my files is watching some videos that obviously can chew through a few GB cache quickly.
This is rather out of date for the 3.x kernels, but here's a pretty good tuning guide for RHEL 6 systems (2.6 kernel)...
https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/6/ht...
I'll check that out. Most of the tunables haven't changed since 2.6
Have you tried setting swappiness all the way to 100? Did that have no effect?
I'll try that next. The more I read about swappiness, the more I get confused whether in my case I want it set closer to 0 or closer to 100. I thought 100, but it really doesn't frame things in terms of cache/buffers.
Adding more RAM might be another option. :)
Older box with ECC, and 8 is the max (I have 4 sticks of 2), I think, but I will double-check as RAM has gotten so cheap. However, if I'm looking at a $200 RAM bill (I think I paid $500 for the existing 8GB?) then I'd be more likely to use it as a chance to get a whole new ECC box :-)