memory mgmt/tuning for diskless machines
Hi,
I'm working on a project for building diskless multimedia terminals/game consoles. One issue I'm having is my terminal seems to go OOM and crash from time to time. It's strange, I would expect the OOM killer to blow away X, but it doesn't - the machine just becomes unresponsive.
Since this is a quasi-embedded platform, what I'd REALLY like to do is tune the vm so mallocs fail when freepages falls below a certain point. I'm using cramfs, and what I suspect is happening is that once memory gets too low, the kernel doesn't have enough memory to uncompress pages. Since there's no swap, there's nothing to page out.
So... it occured to me I could tune this with /proc/sys/vm/freepages - but now I find that it's read-only, and I can't echo x y z > freepages like I used to. What's up with that?
Suggestions?
regards,
David
Signature · 7 lines
David L. Parsley Network Administrator Roanoke College -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM, see: http://www.linux.eu.org/Linux-MM/
Quoted 7 lines · David L. Parsley
I'm working on a project for building diskless multimedia terminals/game consoles. One issue I'm having is my terminal seems to go OOM and crash from time to time. It's strange, I would expect the OOM killer to blow away X, but it doesn't - the machine just becomes unresponsive.
Since this is a quasi-embedded platform, what I'd REALLY like to do is tune the vm so mallocs fail when freepages falls below a certain point.
Hi David,
I think you might want to talk with Jonathan Morton about your situation. Jonathan is working on a non-overcommit patch which will make sure no more memory is malloc()ed than what is available.
Chances are this patch will stay separate for the kernel for some more time and get integrated later when it is well-tested and there is a certain userbase who really want/need the patch (I suspect both of these will happen rather soon, though;)).
regards,
Rik
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Quoted 11 lines · Rik van Riel
Quoted 7 lines · David L. Parsley
I'm working on a project for building diskless multimedia terminals/game consoles. One issue I'm having is my terminal seems to go OOM and crash from time to time. It's strange, I would expect the OOM killer to blow away X, but it doesn't - the machine just becomes unresponsive.
Since this is a quasi-embedded platform, what I'd REALLY like to do is tune the vm so mallocs fail when freepages falls below a certain point.
Quoted 6 lines
Hi David,
I think you might want to talk with Jonathan Morton about your situation. Jonathan is working on a non-overcommit patch which will make sure no more memory is malloc()ed than what is available.
Thanks Rick, I'll bet you're right. I changed the sysctl registration to make /proc/sys/vm/freepages read-write, and even playing with it for a while it was a no-win. Either 1) the machine would become unresponsive, or 2) X would crash. For embedded systems, the non-over-commit patch is almost certainly the way to go - and we all know how popular embedded Linux is these days. ;-)
I'll try to search for his patch in kernel archives and let you know how it works out.
Jonathan - if you could ship me the patch I'd appreciate it, but I'll try searching first.
regards,
David
Signature · 7 lines
David L. Parsley Network Administrator Roanoke College -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM, see: http://www.linux.eu.org/Linux-MM/
Quoted 5 lines
I'll try to search for his patch in kernel archives and let you know how it works out.
Jonathan - if you could ship me the patch I'd appreciate it, but I'll try searching first.
Search the last few days for a post beginning "[TAKE3] [PATCH]"...
Note there is a bug in the accounting which appears to be able to cause the count of reserved memory to go negative under some circumstances. I triggered it by starting 4 copies of the Blackdown Java 1.2.2 VM, then closing them. With the patch enabled, two extra fields appear in /proc/meminfo for monitoring.
Note also that I'm not sbscribed on the linux-mm list (perhaps I should be), so please CC me.
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Quoted 13 lines · David L. Parsley
Hi,
I'm working on a project for building diskless multimedia terminals/game consoles. One issue I'm having is my terminal seems to go OOM and crash from time to time. It's strange, I would expect the OOM killer to blow away X, but it doesn't - the machine just becomes unresponsive.
Since this is a quasi-embedded platform, what I'd REALLY like to do is tune the vm so mallocs fail when freepages falls below a certain point. I'm using cramfs, and what I suspect is happening is that once memory gets too low, the kernel doesn't have enough memory to uncompress pages. Since there's no swap, there's nothing to page out.
Quoted 3 lines
So... it occured to me I could tune this with
/proc/sys/vm/freepages- but now I find that it's read-only, and I can't echo x y z > freepages like I used to. What's up with that?
It should work. Are you sure you're trying to change it as root ?
Quoted 1 line
Suggestions?
Which kernel version are you using ?
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