On Wed, 19 Feb 2014 09:59:17 +0100 Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > On Tue, Feb 18, 2014 at 05:12:43PM -0500, riel@xxxxxxxxxx wrote: > > The NUMA scanning code can end up iterating over many gigabytes > > of unpopulated memory, especially in the case of a freshly started > > KVM guest with lots of memory. > > > > This results in the mmu notifier code being called even when > > there are no mapped pages in a virtual address range. The amount > > of time wasted can be enough to trigger soft lockup warnings > > with very large (>2TB) KVM guests. > > > > This patch moves the mmu notifier call to the pmd level, which > > represents 1GB areas of memory on x86-64. Furthermore, the mmu > > notifier code is only called from the address in the PMD where > > present mappings are first encountered. > > > > The hugetlbfs code is left alone for now; hugetlb mappings are > > not relocatable, and as such are left alone by the NUMA code, > > and should never trigger this problem to begin with. > > > > The series also adds a cond_resched to task_numa_work, to > > fix another potential latency issue. > > Andrew, I'll pick up the first kernel/sched/ patch; do you want the > other two mm/ patches? That works, thanks. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
