Something is deeply broken in OS X memory management

Post by hughw » Mon, Apr 23, 2012, 6:31 PM UTC

eridius wrote: post #92

collint wrote: post #2

You can run `purge` in a terminal to free your 'inactive' ram. I've set up a cron job to purge frequently, keeps thing humming.

That's a terrible idea. `purge` is not a tool for freeing inactive ram. It's a tool for deleting the filesystem cache in order to simulate cold boot conditions for performance analysis. Yes, it has the side effect of reducing memory usage, inasmuch as it's throwing away stuff that was kept in memory. But that doesn't make it an appropriate tool to use.

Post by danboarder » Mon, Apr 23, 2012, 6:36 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…

Post by calinet6 » Mon, Apr 23, 2012, 6:36 PM UTC

gurkendoktor wrote: post #12

ComputerGuru wrote: post #10

Earlier quoted context omitted.

I upgraded to an SSD while on Leopard, and was amazed at the speed. Snow Leopard continued to impress. Lion slowed things down terribly (even with the SSD!), but I have good news: ever since Mountain Lion DP2, it's been fast again.

Yes, I am a fan of ML so far too. Given that Apple has fixed none of my reported bugs in 10.7, but I can't reproduce many of them in 10.8, I wonder if it even makes sense to analyze 10.7 anymore - seems it's a done deal for Apple.

Post by lobster_johnson » Mon, Apr 23, 2012, 6:37 PM UTC

spudlyo wrote: post #55

What really needs to happen is that Spotlight and Time Machine need to use direct i/o (F_NOCACHE) when they read data from the filesystem, this way they won't pollute the disk cache with their reads and OSX won't swap out a bunch of pages in response. I think you could probably hack something together that does this with DYLD_INSERT_LIBRARIES (OSX's LD_PRELOAD) that would would hook the open system call and fcntl F_N…

Post by rhizome » Mon, Apr 23, 2012, 6:40 PM UTC

thought_alarm wrote: post #59

carguy1983 wrote: post #51

I have an 8-way Xeon Mac Pro w/ 20GB of RAM, almost half of which is 'free' at any point during the day unless I'm doing something really out of the ordinary. Yet it still swaps to disk ALL THE TIME and a new Terminal.app window can take up to 5 seconds to open. I really don't give a shit how it's not "technically" broken - that's broken from an experience point of view. And I haven't re-installed the OS (this was an…

Yet it still swaps to disk ALL THE TIME and a new Terminal.app window can take up to 5 seconds to open. That's not swapping. That delay is /usr/bin/login searching the system logs so that it can display the date and time of your last login. Create a .hushlogin file in your home directory to prevent that.