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Date: Thu, 30 Apr 2020 22:48:40 -0400 From: Daniel Jordan <daniel.m.jordan@...cle.com> To: Josh Triplett <josh@...htriplett.org> Cc: Daniel Jordan <daniel.m.jordan@...cle.com>, Andrew Morton <akpm@...ux-foundation.org>, Herbert Xu <herbert@...dor.apana.org.au>, Steffen Klassert <steffen.klassert@...unet.com>, Alex Williamson <alex.williamson@...hat.com>, Alexander Duyck <alexander.h.duyck@...ux.intel.com>, Dan Williams <dan.j.williams@...el.com>, Dave Hansen <dave.hansen@...ux.intel.com>, David Hildenbrand <david@...hat.com>, Jason Gunthorpe <jgg@...pe.ca>, Jonathan Corbet <corbet@....net>, Kirill Tkhai <ktkhai@...tuozzo.com>, Michal Hocko <mhocko@...nel.org>, Pavel Machek <pavel@....cz>, Pavel Tatashin <pasha.tatashin@...een.com>, Peter Zijlstra <peterz@...radead.org>, Randy Dunlap <rdunlap@...radead.org>, Shile Zhang <shile.zhang@...ux.alibaba.com>, Tejun Heo <tj@...nel.org>, Zi Yan <ziy@...dia.com>, linux-crypto@...r.kernel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH 0/7] padata: parallelize deferred page init 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@...htriplett.org> Appreciate the runs, Josh, thanks.
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