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Help, Linux ate my RAM

linuxatemyram.com

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Re: Help, Linux ate my RAM

#91

Post by scott_s »

jff wrote: post #89
scott_s wrote: post #55

Earlier quoted context omitted.

I suspect you don't know what virtual memory is: http://news.ycombinator.com/item?id=3699481

Yes, I know what virtual memory is, I'm a computer engineer and I work on operating systems. I'm just extremely impressed that they needed 1.5 GB of address space, for christ's sake. Insert here some pithy comment about Apollo missions and Twitter, or whatever.

The reason I suspected that is grabbing 1.5 GB of virtual memory doesn't mean much. It just means you asked the OS to change its book-keeping to allow you to access that much. Applications and libraries that aggressively cache and prefetch routinely do that sort of thing.

Re: Help, Linux ate my RAM

#92

Post by seclorum »

ivan78 wrote: post #63
seclorum wrote: post #52

Earlier quoted context omitted.

Teach them to interpret and understand cat /proc/meminfo .. one of the most interesting things you can do with this is pipe it into gnuplot and watch it over time as things happen. Try it sometimes .. you might get through to one or two.

If you want to be more enterprisey, you can pipe it to SNMP counter and then draw a graph with your Network Monitoring System. It is much more convenient if you have more that few servers.

Maybe that's more 'enterprisey', but its more 'system administrator'-ey to just use an onboard gnuplot and look at real graphs without putting much SNMP/traffic-load on the system of interest .. the purpose is to educate the user on how the system works, not use it as a monitoring device for lazy sysadmins.

Re: Help, Linux ate my RAM

#93

Post by mgedmin »

Steve_Baker wrote: post #32
francoisdevlin wrote: post #24

Earlier quoted context omitted.

Okay, I'm one of those devs. What is this virtual/resident set size thing you're talking about? EDIT: Thank you for all the helpful responses!

The virtual size of a program includes all shared objects (shared libraries, shared copy on write memory pages, the read only executable pages and other shared memory) that a process uses in addition to the memory that only that particular process is using (its resident set size.) Shared objects like shared libraries can be mapped into memory by multiple processes and thus don't use any additional physical memory for…

RSS also includes shared memory pages (those that are currently resident).

Re: Help, Linux ate my RAM

#94

Post by mgedmin »

sciurus wrote: post #73
Legion wrote: post #38

Earlier quoted context omitted.

2 minute fix: get people to use htop, not top.

Having tried both, I'd recommend atop over htop. There's a great overview of its capabilities at https://lwn.net/Articles/387202/

While more powerful, atop is rather confusing. htop is friendly.

Re: Help, Linux ate my RAM

#95

Post by dchest »

jff wrote: post #89
scott_s wrote: post #55

Earlier quoted context omitted.

I suspect you don't know what virtual memory is: http://news.ycombinator.com/item?id=3699481

Yes, I know what virtual memory is, I'm a computer engineer and I work on operating systems. I'm just extremely impressed that they needed 1.5 GB of address space, for christ's sake. Insert here some pithy comment about Apollo missions and Twitter, or whatever.

The reason for acquiring a lot of virtual memory is to save memory and improve performance.

Re: Help, Linux ate my RAM

#96

Post by mgedmin »

ineedtosleep wrote: post #49
jff wrote: post #17

Earlier quoted context omitted.

Yep, firefox is currently 555 MB resident and using 1.5 GIGABYTES of virtual memory space. Goddamn, firefox, you are a pig . Saddest thing? I've got gmail, github, and maybe 10 static pages open. Linux just looks like it ate your RAM. Firefox straight up does eat it.

Why is Firefox always mentioned in this context? Sure they have had a history of it, but lately they've been fine and if one compares the combined spawned processes of Chrome, Chrome typically has more memory consumption.

The ongoing efforts of the MemShrink project keep finding memory leaks -- usually in Firefox addons. You can read more about it at http://blog.mozilla.com/nnethercote/category/memshrink/

Re: Help, Linux ate my RAM

#97

Post by mgedmin »

ez77 wrote: post #85

I found this page because I was pretty confused about these issues, and still am... Question for the crowd: In this site the example given says that in reality there are 869MB of used RAM. I'm comparing this with my VPS values, and would like to know if this is the sum of some column in top. Is it? It looks like it's pretty close to the sum of the SHR column. Does this make sense? Thanks in advance.

You can't really do sums of top columns, because some memory is shared and you'll end up double-counting it.

And you can't just subtract the shared memory numbers, because different sets of pages are shared between different sets of processes, and top doesn't give enough information to figure out what's actually happening where.

Running the pmaps tool on all pids and summing the Pss number is perhaps the closest you can get to the actual memory use.

Re: Help, Linux ate my RAM

#98

Post by makomk »

calloc wrote: post #82
ineedtosleep wrote: post #49

Earlier quoted context omitted.

Why is Firefox always mentioned in this context? Sure they have had a history of it, but lately they've been fine and if one compares the combined spawned processes of Chrome, Chrome typically has more memory consumption.

Remember that when you are accounting for those you also need to remove all of the stuff that is paged into every process and is the same across them, such as shared libraries and the like. Most likely Chrome is using less ram than you think.

Chrome has a built-in task manager that takes this into account, as well as a slightly more hidden "Stats for nerds" link in the task manager that gives total memory usage. It's just genuinely very memory hungry once you add up all its processes.

Re: Help, Linux ate my RAM

#99

Post by mwexler »

ineedtosleep wrote: post #49
jff wrote: post #17

Earlier quoted context omitted.

Yep, firefox is currently 555 MB resident and using 1.5 GIGABYTES of virtual memory space. Goddamn, firefox, you are a pig . Saddest thing? I've got gmail, github, and maybe 10 static pages open. Linux just looks like it ate your RAM. Firefox straight up does eat it.

Why is Firefox always mentioned in this context? Sure they have had a history of it, but lately they've been fine and if one compares the combined spawned processes of Chrome, Chrome typically has more memory consumption.

I keep my Firefox up to date with release versions, have few plugins, and still find it absorbing memory at a tremendous rate. Chrome can also use memory, but somehow manages to let it go sometimes, as well as not drag my entire (Windows) system to a stutter.

I guess so many of us mention FF in this context because it still happens to us, even though we gamely continue to use it. But we still love it, and that's why we continue to use it. Though admittedly, most of us have a Chrome on the side...

Re: Help, Linux ate my RAM

#100

Post by mwexler »

pcwalton wrote: post #41
jff wrote: post #17

Earlier quoted context omitted.

Yep, firefox is currently 555 MB resident and using 1.5 GIGABYTES of virtual memory space. Goddamn, firefox, you are a pig . Saddest thing? I've got gmail, github, and maybe 10 static pages open. Linux just looks like it ate your RAM. Firefox straight up does eat it.

What does about:memory say?

Putting that in Chrome gets me to a page that was new to me, chrome://memory-redirect/
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