On Fri, Apr 15, 2016 at 3:31 PM, Rik van Riel <riel@xxxxxxxxxx> wrote: > On Fri, 2016-04-15 at 12:15 -0700, Andrew Morton wrote: >> (switched to email. Please respond via emailed reply-to-all, not via >> the >> bugzilla web interface). >> >> This is ... interesting. > > First things first. What is the value of > /proc/sys/vm/zone_reclaim? There is no such thing on this system. However: $ cat /proc/sys/vm/zone_reclaim_mode 0 > > I am assuming this is a two socket system, > with two 12-core CPUs. Am I right? Yes. > >> On Thu, 12 Nov 2015 18:46:35 +0000 bugzilla- >> daemon@xxxxxxxxxxxxxxxxxxx wrote: >> >> > >> > https://bugzilla.kernel.org/show_bug.cgi?id=107771 >> > >> > Bug ID: 107771 >> > Summary: Single process tries to use more than 1/2 >> > physical >> > RAM, OS starts thrashing >> > Product: Memory Management >> > Version: 2.5 >> > Kernel Version: 4.3.0-040300-generic (Ubuntu) >> > Hardware: All >> > OS: Linux >> > Tree: Mainline >> > Status: NEW >> > Severity: normal >> > Priority: P1 >> > Component: Page Allocator >> > Assignee: akpm@xxxxxxxxxxxxxxxxxxxx >> > Reporter: theosib@xxxxxxxxx >> > Regression: No >> > >> > I have a 24-core (48 thread) system with 64GB of RAM. >> > >> > When I run multiple processes, I can use all of physical RAM before >> > swapping >> > starts. However, if I'm running only a *single* process, the >> > system will start >> > swapping after I've exceeded only 1/2 of available physical >> > RAM. Only after >> > swap fills does it start using more of the physical RAM. >> > >> > I can't find any ulimit settings or anything else that would cause >> > this to >> > happen intentionally. >> > >> > I had originally filed this against Ubuntu, but I'm now running a >> > more recent >> > kernel, and the problem persists, so I think it's more appropriate >> > to file >> > here. There are some logs that they had me collect, so if you want >> > to see >> > them, the are here: >> > >> > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1513673 >> > >> > I don't recall this problem happening with older kernels (whatever >> > came with >> > Ubuntu 15.04), although I may just not have noticed. By swapping >> > early, I'm >> > limited by the speed of my SSD, which is moving only about 20MB/sec >> > in each >> > direction, and that makes what I'm running take 10 times as long to >> > complete. >> > > -- > All Rights Reversed. > -- Timothy Normand Miller, PhD Assistant Professor of Computer Science, Binghamton University http://www.cs.binghamton.edu/~millerti/ Open Graphics Project -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>