Something is deeply broken in OS X memory management • Hacker News Board

Re: Something is deeply broken in OS X memory management

#41

Post by jsolson » Mon, Apr 23, 2012, 4:42 PM UTC

gurkendoktor wrote: post #8

w0utert wrote: post #4

Not this again, we already went through this a few weeks ago. Back then, I thought the conclusion was that there is nothing broken about OS X memory management, and that with every 'fix' you come up with, you will just introduce another degenerate corner case. The same holds for any OS, trade-offs are made that may have some negative effect in some cases, to the benefit of the general cases. I don't recognize any of…

The thing is, Lion runs like crap without an SSD or insane amounts of RAM for many people. It doesn't help if it works for some, or even the majority. If anything, we need more people digging in OS X internals. I am sorry to use a tired analogy here, but Vista did work great for many too. I have two Macs, one brand new, one migrated from SL, and 10.7 Safari was almost unusable on both until I installed SSDs. If that…

> The thing is, Lion runs like crap without an SSD or insane amounts of RAM for many people.

YES. I have a MacBook Pro Core i7 from a little while back with an old style spinning rust drive and a 11" MacBook Air Core 2 Duo.

For purely CPU bound things, sure, the Core i7 kicks the pants out of the Core 2. Same for videogames. For day to day use, though, switching between Eclipse, Xcode, Chrome, etc. the Air provides a much more uniform experience. At its best it's far slower than the Pro at its best, but at its worst it's much faster and more responsive. I rarely see beachballs on the Air. I used to see them all the time on the Pro (the Pro has been sitting on a shelf for the past eight months as I switched to working exclusively on my Air, partially for this reason).

So my experience is that something may not be broken, but something definitely isn't set up optimally for users with poor disk performance and high memory/CPU performance.

Re: Something is deeply broken in OS X memory management

#42

Post by stephencanon » Mon, Apr 23, 2012, 4:42 PM UTC

jfb wrote: post #37

bsimpson wrote: post #17

I've been a Mac user since the beginning, and by far my biggest frustration is the perpetual running-out-of-RAM, even when I close basically everything. I have 4GB of RAM, and frequently catch kernel_task using at least half of it.

Why shouldn't the kernel be using as much memory as possible? It's not like big disk caches or what have you cause your memory to go bad? As long as you get it back when you need it, who cares ?

This. Memory that is not used is wasted. If you spend a bunch of money on a high-memory setup, you should be furious if the OS doesn't use it all.

Re: Something is deeply broken in OS X memory management

#43

Post by colomon » Mon, Apr 23, 2012, 4:43 PM UTC

obituary_latte wrote: post #22

w0utert wrote: post #4

Not this again, we already went through this a few weeks ago. Back then, I thought the conclusion was that there is nothing broken about OS X memory management, and that with every 'fix' you come up with, you will just introduce another degenerate corner case. The same holds for any OS, trade-offs are made that may have some negative effect in some cases, to the benefit of the general cases. I don't recognize any of…

>I don't recognize any of his symptoms anyway, and my OS X computers get pretty RAM-heavy use, with almost always a linux VM open, XCode, Safari with ~10 tabs, iTunes with a few thousand songs, etc. Oh boy I wish I could say the same. Admittedly I don't shut down on a daily basis but this didn't used to be a problem in SL. FWIW I've an old tank of a tower that has a video card on its last leg.. shutting down invariab…

For what it's worth, I'm running Snow Leopard (10.6.8) and I see the same sort of terrible performance the article describes.

Though I did improve matters drastically by telling mds not to index my (Linux) MP3 server and my Time Machine drive. That made it go from nearly unusable to just frequently annoying.

The other crazy thing I've been seeing is it routinely takes Chrome minutes to shutdown -- in fact, pretty much every time I try to reboot my MBP without shutting down Chrome first, the shutdown process times out trying to exit Chrome.

Re: Something is deeply broken in OS X memory management

#44

Post by raverbashing » Mon, Apr 23, 2012, 4:45 PM UTC

gurkendoktor wrote: post #8

w0utert wrote: post #4

Not this again, we already went through this a few weeks ago. Back then, I thought the conclusion was that there is nothing broken about OS X memory management, and that with every 'fix' you come up with, you will just introduce another degenerate corner case. The same holds for any OS, trade-offs are made that may have some negative effect in some cases, to the benefit of the general cases. I don't recognize any of…

The thing is, Lion runs like crap without an SSD or insane amounts of RAM for many people. It doesn't help if it works for some, or even the majority. If anything, we need more people digging in OS X internals. I am sorry to use a tired analogy here, but Vista did work great for many too. I have two Macs, one brand new, one migrated from SL, and 10.7 Safari was almost unusable on both until I installed SSDs. If that…

This

I haven't tried ML yet. My MBP is brand new (bought in January 2012), factory configuration (4GB RAM, Lion)

If you use it 'lightly' (that is, only Safari open) it's a breeze. But of course, it's never only that if you want to do any work.

Frankly, 4 GB should be enough! My past machine (with 3GB - and Linux) would rarely swap (in fact I could keep swap off and use a Windows 7 VM) But you can go only so far with an aging CPU

Some of the slowness can be attributed to Safari/Firefox, sure

But it really seems to have something wrong. Maybe they really neglected people with spinning disks.

(Yes, I considered buying a MacBook Air but 128Gb was not enough for me and the other options were above my budget)

Re: Something is deeply broken in OS X memory management

#45

Post by seanalltogether » Mon, Apr 23, 2012, 4:46 PM UTC

obituary_latte wrote: post #22

w0utert wrote: post #4

Not this again, we already went through this a few weeks ago. Back then, I thought the conclusion was that there is nothing broken about OS X memory management, and that with every 'fix' you come up with, you will just introduce another degenerate corner case. The same holds for any OS, trade-offs are made that may have some negative effect in some cases, to the benefit of the general cases. I don't recognize any of…

>I don't recognize any of his symptoms anyway, and my OS X computers get pretty RAM-heavy use, with almost always a linux VM open, XCode, Safari with ~10 tabs, iTunes with a few thousand songs, etc. Oh boy I wish I could say the same. Admittedly I don't shut down on a daily basis but this didn't used to be a problem in SL. FWIW I've an old tank of a tower that has a video card on its last leg.. shutting down invariab…

I had to shut down on a daily basis because of this problem with my system having only 4 GB of ram. There is definitely something broken in there.

http://i.imgur.com/ohBEF.png

Re: Something is deeply broken in OS X memory management

#46

Post by Flow » Mon, Apr 23, 2012, 4:50 PM UTC

gurkendoktor wrote: post #8

w0utert wrote: post #4

Not this again, we already went through this a few weeks ago. Back then, I thought the conclusion was that there is nothing broken about OS X memory management, and that with every 'fix' you come up with, you will just introduce another degenerate corner case. The same holds for any OS, trade-offs are made that may have some negative effect in some cases, to the benefit of the general cases. I don't recognize any of…

The thing is, Lion runs like crap without an SSD or insane amounts of RAM for many people. It doesn't help if it works for some, or even the majority. If anything, we need more people digging in OS X internals. I am sorry to use a tired analogy here, but Vista did work great for many too. I have two Macs, one brand new, one migrated from SL, and 10.7 Safari was almost unusable on both until I installed SSDs. If that…

I have 12GB of RAM and Lion runs like crap on my iMac 2.93GHz i7.

It's like the system discards pages of programs just because the app has been inactive for an hour or so. So when I come back and start the same app the f*cking rotating HD I have sounds like a birds nest for too long periods.

Edit: Disabled the pager and the system now seems much more quiet regarding to disk seek noise when I start apps. Feels like a new machine! :-D

Re: Something is deeply broken in OS X memory management

#47

Post by DrJokepu » Mon, Apr 23, 2012, 4:50 PM UTC

krakensden wrote: post #38

jfb wrote: post #37

Earlier quoted context omitted.

Why shouldn't the kernel be using as much memory as possible? It's not like big disk caches or what have you cause your memory to go bad? As long as you get it back when you need it, who cares ?

Because he's not getting it back when he needs it?

Recent Windows NT kernels, recent Linux kernels and recent Darwin kernels will drop disk cache pages the moment something more important needs them. Memory management in modern kernels can be very complicated and just because it appears that a process does a lot of paging it doesn't necessarily mean that it needs more physical memory.

Re: Something is deeply broken in OS X memory management

#48

Post by tomc1985 » Mon, Apr 23, 2012, 4:51 PM UTC

I did this for awhile and ran into an interesting (if fatal) edge case:

I use a 1.5tb external drive formatted in exFAT to minimize cross-platform headaches, and whenever the drive is marked dirty (improper shutdown, eject, etc), OSX will run fsck_exfat on it before I can use it.

fsck_exfat isn't a huge deal -- or wouldn't be, if it didn't have a nasty tendency to leak RAM... the moment you plug in, fsck_exfat's footprint climbs up and up and up... never stopping! Pretty soon it's eaten up 8gb out of my 8gb RAM and poor ol' lappy is unusable.

I can say with authority what happens when you run out of physical RAM in OSX: it hard locks. Nothing works -- no keyboard, no mouse, nothing.

So, if you plug in your large, dirty (you dirty drive you!) exFAT-formatted external drive, with dynamic_paging switched off, and let fsck_exfat do its thing, your laptop freezes! Leaving the drive dirty, only to be re-scan on boot-up... freezing the laptop, leaving the drive dirty, only to be re-scan on bootup...

EDIT: this is with Snow Leopard...

Re: Something is deeply broken in OS X memory management

#49

Post by coffeedrinker » Mon, Apr 23, 2012, 4:51 PM UTC

deweller wrote: post #31

I had a similar problems with my Mac slowing down to a crawl with certain instances of disk access. I tried turning off spotlight (which was taking a very long time to complete) but it did not help. For me, the problem turned out to be a failing hard drive. After replacing my system hard drive, things returned to normal speed. I'm just posting this in case it might help someone else.

I concur. I've seen this exact behavior on two different systems when the hard drive was beginning to fail. Swapping the drive fixed the problem.

My friend had installed a new larger drive that was causing the problem, whereas there were no beach balls while booting off the original drive via USB.

Re: Something is deeply broken in OS X memory management

#50

Post by frou_dh » Mon, Apr 23, 2012, 4:52 PM UTC

SkyMarshal wrote: post #40

dreish wrote: post #20

Earlier quoted context omitted.

Probably a lot of people hitting the up arrow to save the link to try out this evening. I plead guilty to doing that. I wish I'd read the comments first.

I do that too sometimes. Wtb separate save button.

http://www.instapaper.com/