[Kernel-packages] [Bug 159356] Re: When DMA is disabled system freeze on high memory usage
I am running on a ~9 year laptop with 1866MiB ram and 3933MiB swap. Lubuntu installed. Linux ub2 4.18.0-16-generic #17-Ubuntu SMP Fri Feb 8 00:06:57 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux So my problem is for example, having two different browsers open with too many open browser tabs (4-6) on each caused a high memory load with system freeze. I noticed that swap was not being used in a why that I think it should be, that is a general slow down as more and more swap was used. Instead I got instant freeze for 30 minutes or more. So I found a program called munch.c and played around with it. I also created different versions of munch.c so memory usage was different. I was able to change system vm settings (in /proc/sys/vm) so the freeze stopped and swap started to be used correctly so that real memory and virtual memory became balanced. I define "balanced" to mean as more swap is used the system gradually becomes slower without freezing. In fact in the beginning the Linux-memory-swap system was very poor (default settings) and a Microsoft Windows 7 machine with same memory far far better at memory-swap management. My conclusion (for now) is that by altering default settings the Linux system became much better because the freeze bug was eliminated. I turned on the SysRq feature to enable the (f) option. I found I could make the SysRq (f) work straight away. Also found the automatic OOM now kicked in as well, if I waited a bit. I will add more details to this at a later time. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/159356 Title: When DMA is disabled system freeze on high memory usage Status in linux package in Ubuntu: Incomplete Status in linux package in Arch Linux: New Bug description: I run a batch matlab job server here at my lab, running Dapper 6.06 (for the LTS). One of the users has submitted a very memory-consuming job, which successfully crashes the server. Upon closer inspection, the crash happens like this: 1. I run matlab with the given file (as an ordinary, unpriveleged user) 2. RAM usage quickly fills up 3. Once the RAM meter hits 100%, the system freezes: All SSH connections freeze up, and while switching VTs directly on the machine works, no new processes run - so one can't log in, or do anything if he is logged in. (Sometimes typing doesn't work at all) Note that the swap - while 7 gigs of it are available - is never used. (The machine has 7 gigs of RAM as well) I've tried the same on my Gutsy 32-bit box, and there was no system freezeup - matlab simply notified that the system was out of memory. However, it did this once memory was 100% in use - and still, swap didn't get used at all! (Though it is mounted correctly and shows up in "top" and "free"). So first thing's first - I'd like to eliminate the crash issue. I suppose I could switch the server to 32-bit, but I think that would be a performance loss, considering that it does a lot of heavy computation. There is no reason, however, that this should happen on a 64-bit machine anyway. Why does it? WORKAROUND: Enabling DMA in the BIOS To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/159356/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
[Kernel-packages] [Bug 159356] Re: When DMA is disabled system freeze on high memory usage
Further, to my comment above, if I enable swap, the program continues to run using up all the swap, and then terminates without a system freeze. The program pauses for about 1/3 second intervals as swap gets used. The higher vm.min_free_kbytes the pauses are less. I have a third memory eater and I managed to get up to 66 Gb virtual memory allocated. My old laptop (9 years) has only 2Gb Ram. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/159356 Title: When DMA is disabled system freeze on high memory usage Status in linux package in Ubuntu: Incomplete Status in linux package in Arch Linux: New Bug description: I run a batch matlab job server here at my lab, running Dapper 6.06 (for the LTS). One of the users has submitted a very memory-consuming job, which successfully crashes the server. Upon closer inspection, the crash happens like this: 1. I run matlab with the given file (as an ordinary, unpriveleged user) 2. RAM usage quickly fills up 3. Once the RAM meter hits 100%, the system freezes: All SSH connections freeze up, and while switching VTs directly on the machine works, no new processes run - so one can't log in, or do anything if he is logged in. (Sometimes typing doesn't work at all) Note that the swap - while 7 gigs of it are available - is never used. (The machine has 7 gigs of RAM as well) I've tried the same on my Gutsy 32-bit box, and there was no system freezeup - matlab simply notified that the system was out of memory. However, it did this once memory was 100% in use - and still, swap didn't get used at all! (Though it is mounted correctly and shows up in "top" and "free"). So first thing's first - I'd like to eliminate the crash issue. I suppose I could switch the server to 32-bit, but I think that would be a performance loss, considering that it does a lot of heavy computation. There is no reason, however, that this should happen on a 64-bit machine anyway. Why does it? WORKAROUND: Enabling DMA in the BIOS To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/159356/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
[Kernel-packages] [Bug 159356] Re: When DMA is disabled system freeze on high memory usage
Try increasing vm.min_free_kbytes I have two memory eater programs, one uses 1Mb steps and the other 1Kb steps. When I run the 1Mb, the oom killer cuts in. When I run the 1Kb program the oom does not. If I raise the vm.min_free_kbytes = 17-25 both programs are terminated, no system freeze. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/159356 Title: When DMA is disabled system freeze on high memory usage Status in linux package in Ubuntu: Incomplete Status in linux package in Arch Linux: New Bug description: I run a batch matlab job server here at my lab, running Dapper 6.06 (for the LTS). One of the users has submitted a very memory-consuming job, which successfully crashes the server. Upon closer inspection, the crash happens like this: 1. I run matlab with the given file (as an ordinary, unpriveleged user) 2. RAM usage quickly fills up 3. Once the RAM meter hits 100%, the system freezes: All SSH connections freeze up, and while switching VTs directly on the machine works, no new processes run - so one can't log in, or do anything if he is logged in. (Sometimes typing doesn't work at all) Note that the swap - while 7 gigs of it are available - is never used. (The machine has 7 gigs of RAM as well) I've tried the same on my Gutsy 32-bit box, and there was no system freezeup - matlab simply notified that the system was out of memory. However, it did this once memory was 100% in use - and still, swap didn't get used at all! (Though it is mounted correctly and shows up in "top" and "free"). So first thing's first - I'd like to eliminate the crash issue. I suppose I could switch the server to 32-bit, but I think that would be a performance loss, considering that it does a lot of heavy computation. There is no reason, however, that this should happen on a 64-bit machine anyway. Why does it? WORKAROUND: Enabling DMA in the BIOS To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/159356/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
