On Mon, Aug 15, 2016 at 10:22:43AM -0700, Huang, Ying wrote: > Hi, Chinner, > > Dave Chinner <da...@fromorbit.com> writes: > > > On Wed, Aug 10, 2016 at 06:00:24PM -0700, Linus Torvalds wrote: > >> On Wed, Aug 10, 2016 at 5:33 PM, Huang, Ying <ying.hu...@intel.com> wrote: > >> > > >> > Here it is, > >> > >> Thanks. > >> > >> Appended is a munged "after" list, with the "before" values in > >> parenthesis. It actually looks fairly similar. > >> > >> The biggest difference is that we have "mark_page_accessed()" show up > >> after, and not before. There was also a lot of LRU noise in the > >> non-profile data. I wonder if that is the reason here: the old model > >> of using generic_perform_write/block_page_mkwrite didn't mark the > >> pages accessed, and now with iomap_file_buffered_write() they get > >> marked as active and that screws up the LRU list, and makes us not > >> flush out the dirty pages well (because they are seen as active and > >> not good for writeback), and then you get bad memory use. > >> > >> I'm not seeing anything that looks like locking-related. > > > > Not in that profile. I've been doing some local testing inside a > > 4-node fake-numa 16p/16GB RAM VM to see what I can find. > > You run the test in a virtual machine, I think that is why your perf > data looks strange (high value of _raw_spin_unlock_irqrestore). > > To setup KVM to use perf, you may refer to, > > https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Virtualization_Tuning_and_Optimization_Guide/sect-Virtualization_Tuning_Optimization_Guide-Monitoring_Tools-vPMU.html > https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization_Administration_Guide/sect-perf-mon.html > > I haven't tested them. You may Google to find more information. Or the > perf/kvm people can give you more information.
Thanks, "-cpu host" on the qemu command line works. I hate magic, undocumented(*) features that are necessary to make basic stuff work. -Dave. (*) yeah, try working this capability even exists out from the qemu/kvm man page. -- Dave Chinner da...@fromorbit.com
