On Thu, Apr 30, 2020 at 06:09:35PM -0700, Josh Triplett wrote: > On Thu, Apr 30, 2020 at 04:11:18PM -0400, Daniel Jordan wrote: > > Sometimes the kernel doesn't take full advantage of system memory > > bandwidth, leading to a single CPU spending excessive time in > > initialization paths where the data scales with memory size. > > > > Multithreading naturally addresses this problem, and this series is the > > first step. > > > > It extends padata, a framework that handles many parallel singlethreaded > > jobs, to handle multithreaded jobs as well by adding support for > > splitting up the work evenly, specifying a minimum amount of work that's > > appropriate for one helper thread to do, load balancing between helpers, > > and coordinating them. More documentation in patches 4 and 7. > > > > The first user is deferred struct page init, a large bottleneck in > > kernel boot--actually the largest for us and likely others too. This > > path doesn't require concurrency limits, resource control, or priority > > adjustments like future users will (vfio, hugetlb fallocate, munmap) > > because it happens during boot when the system is otherwise idle and > > waiting on page init to finish. > > > > This has been tested on a variety of x86 systems and speeds up kernel > > boot by 6% to 49% by making deferred init 63% to 91% faster. Patch 6 > > has detailed numbers. Test results from other systems appreciated. > > > > This series is based on v5.6 plus these three from mmotm: > > > > mm-call-touch_nmi_watchdog-on-max-order-boundaries-in-deferred-init.patch > > mm-initialize-deferred-pages-with-interrupts-enabled.patch > > mm-call-cond_resched-from-deferred_init_memmap.patch > > > > All of the above can be found in this branch: > > > > git://oss.oracle.com/git/linux-dmjordan.git padata-mt-definit-v1 > > https://oss.oracle.com/git/gitweb.cgi?p=linux-dmjordan.git;a=shortlog;h=refs/heads/padata-mt-definit-v1 > > For the series (and the three prerequisite patches): > > Tested-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx> Appreciate the runs, Josh, thanks.
