On Fri, Jan 01, 2016 at 09:37:52PM +0100, Tor Rune Skoglund wrote: > Hello List, Happy New Year! > Having been a happy linux-vserver user for more than 10 years > now, it was about time to test the hashify feature. The disk > savings are obvious, and easily measured, but I have been > trying a lot harder to measure any possible run-time memory > savings. > For the testing, I created a simple template LAMP guest, and > a lot of hashified guests cloned from that one. I am unable > to measure noticeably less memory usage when running multiple > hashified guests compared to non-hashified ones using free and > /proc/meminfo/'s MemAvailable entry. > However, this could very well be to shortcomings in my own > understanding how this should work or what to look for. > What should I look for regarding possible memory savings? > Anyone with any pointers? You won't see any memory savings with dynamic memory allocations and you won't get any benefits on read-write mappings either, but you should be able to see a reduction for read only mappings like they happen when using static binaries or read only mapped shared libraries as well as read only memory mapped data files. If I would devise a test to show the advantages, I would run a binary which doesn't do many dynamic allocations but uses a lot of code and/or libraries and run it as only process in each guest with a few thousand guests in parallell, once with and without unification in place. Best, Herbert > This is Gentoo, util-vserver 0.30.216_pre3120, kernel Linux amd64 > 3.18.7-vs2.3.7.4. > BR, Tor Rune Skoglund > trs@swi.no >