Op 25-09-14 om 23:10 schreef Peter Hurley: > On 09/25/2014 04:33 PM, Alex Deucher wrote: >> On Thu, Sep 25, 2014 at 2:55 PM, Peter Hurley <peter@xxxxxxxxxxxxxxxxxx> wrote: >>> After several days uptime with a 3.16 kernel (generally running >>> Thunderbird, emacs, kernel builds, several Chrome tabs on multiple >>> desktop workspaces) I've been seeing some really extreme slowdowns. >>> >>> Mostly the slowdowns are associated with gpu-related tasks, like >>> opening new emacs windows, switching workspaces, laughing at internet >>> gifs, etc. Because this x86_64 desktop is nouveau-based, I didn't pursue >>> it right away -- 3.15 is the first time suspend has worked reliably. >>> >>> This week I started looking into what the slowdown was and discovered >>> it's happening during dma allocation through swiotlb (the cpus can do >>> intel iommu but I don't use it because it's not the default for most users). >>> >>> I'm still working on a bisection but each step takes 8+ hours to >>> validate and even then I'm no longer sure I still have the 'bad' >>> commit in the bisection. [edit: yup, I started over] >>> >>> I just discovered a smattering of these in my logs and only on 3.16-rc+ kernels: >>> Sep 25 07:57:59 thor kernel: [28786.001300] alloc_contig_range test_pages_isolated(2bf560, 2bf562) failed >>> >>> This dual-Xeon box has 10GB and sysrq Show Memory isn't showing heavy >>> fragmentation [1]. >>> >>> Besides Mel's page allocator changes in 3.16, another suspect commit is: >>> >>> commit b13b1d2d8692b437203de7a404c6b809d2cc4d99 >>> Author: Shaohua Li <shli@xxxxxxxxxx> >>> Date: Tue Apr 8 15:58:09 2014 +0800 >>> >>> x86/mm: In the PTE swapout page reclaim case clear the accessed bit instead of flushing the TLB >>> >>> Specifically, this statement: >>> >>> It could cause incorrect page aging and the (mistaken) reclaim of >>> hot pages, but the chance of that should be relatively low. >>> >>> I'm wondering if this could cause worse-case behavior with TTM? I'm >>> testing a revert of this on mainline 3.16-final now, with no results yet. >>> >>> Thoughts? >> You may also be seeing this: >> https://lkml.org/lkml/2014/8/8/445 > Thanks Alex. That is indeed the problem. > > Still reading the email thread to find out where the patches > are that fix this. Although it doesn't make much sense to me > that nouveau sets up a 1GB GART and then uses TTM which is > trying to shove all the DMA through a 16MB CMA window > (which turns out to be the base Ubuntu config). > > Regards, > Peter Hurley > > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1362261 CMA's already disabled on x86 in most recent ubuntu kernels. :-) ~Maarten -- 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>