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? I am assuming this is a two socket system, with two 12-core CPUs. Am I right? > 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.
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