what are my CPUs doing?

[SteveRiley]

Why 50%? I googled and clicked for a while and came up with nearly no idea (one reference to 2x) on this, nor what proportion of one's RAM to devote to it.

I was simply using 50% as a placeholder to illustrate the calculation. The amount of compression you can get largely depends on the characteristics of the data in question -- the greater the frequency of repeatable elements, the higher your compression will be.

[jlittle]

Hi guys, just thought I'd relate what I found.

The cause was indeed firefox, but also indeed Google groups web interface.

Back from the days of slow connections, I've been accustomed to clicking through a list of posts to start them loading in separate tabs, so that after finishing reading a post, the next is already loaded and waiting. With Google groups, each newly opened tab would increase firefox's resident set size by 60 to 70 MiB for a few seconds, then drop back to about a 30 MiB increase. Now with firefox running with just one tab, there's only about 160 Mib free, so clicking on a list of posts opening, say, 15 tabs, would produce a peak demand of about 1 GiB of real memory. Such a huge demand quickly crippled things.

I wasn't able to diagnose this using ksysguard because it would react very slowly to the crunch, and by the time it was able to show anything the crunch would be past. Using top and ps as advised here, I was able to see the RSS size jumping up.

I don't know why a tab with a Google groups thread should require so much memory. With rekonq I can't even sign in to Google, I get a screen showing the unrendered HTML (I'm still on Oneiric). I use the same trick with KFN without the same trouble. After I install Precise I'll check out some other browsers.

This computer's 6 years old, and when I got it it had 2 GiB of RAM, but its motherboard failed and I bought a cheap replacement that only has two slots for memory, and I had 0.5 GiB memory sticks, so only 1 GiB, and something, maybe the onboard graphics, uses some of that. I'll investigate buying bigger memory sticks.

Thanks for the help. Regards, John