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From: Peter Zijlstra <peterz@infradead.org>
To: Jason Gunthorpe <jgg@mellanox.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>,
	"rjw@rjwysocki.net" <rjw@rjwysocki.net>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"aarcange@redhat.com" <aarcange@redhat.com>,
	"aaron.lu@intel.com" <aaron.lu@intel.com>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
	"bsd@redhat.com" <bsd@redhat.com>,
	"darrick.wong@oracle.com" <darrick.wong@oracle.com>,
	"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
	"jwadams@google.com" <jwadams@google.com>,
	"jiangshanlai@gmail.com" <jiangshanlai@gmail.com>,
	"mhocko@kernel.org" <mhocko@kernel.org
Subject: Re: [RFC PATCH v4 01/13] ktask: add documentation
Date: Wed, 7 Nov 2018 11:27:52 +0100
Message-ID: <20181107102752.GK9781@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20181106205146.GB30490@mellanox.com>

On Tue, Nov 06, 2018 at 08:51:54PM +0000, Jason Gunthorpe wrote:
> On Tue, Nov 06, 2018 at 12:34:11PM -0800, Daniel Jordan wrote:
> 
> > > What isn't clear is if this calling thread is waiting or not. Only do
> > > this inheritance trick if it is actually waiting on the work. If it is
> > > not, nobody cares.
> > 
> > The calling thread waits.  Even if it didn't though, the inheritance trick
> > would still be desirable for timely completion of the job.
> 
> Can you make lockdep aware that this is synchronous?
> 
> ie if I do
> 
>   mutex_lock()
>   ktask_run()
>   mutex_lock()
> 
> Can lockdep know that all the workers are running under that lock?
> 
> I'm thinking particularly about rtnl_lock as a possible case, but
> there could also make some sense to hold the read side of the mm_sem
> or similar like the above.

Yes, the normal trick is adding a fake lock to ktask_run and holding
that over the actual job. See lock_map* in flush_workqueue() vs
process_one_work().

  reply index

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-05 16:55 [RFC PATCH v4 00/13] ktask: multithread CPU-intensive kernel work Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 01/13] ktask: add documentation Daniel Jordan
2018-11-05 21:19   ` Randy Dunlap
2018-11-06  2:27     ` Daniel Jordan
2018-11-06  8:49   ` Peter Zijlstra
2018-11-06 20:34     ` Daniel Jordan
2018-11-06 20:51       ` Jason Gunthorpe
2018-11-07 10:27         ` Peter Zijlstra [this message]
2018-11-07 20:21           ` Daniel Jordan
2018-11-07 10:35       ` Peter Zijlstra
2018-11-07 21:20         ` Daniel Jordan
2018-11-08 17:26   ` Jonathan Corbet
2018-11-08 19:15     ` Daniel Jordan
2018-11-08 19:24       ` Jonathan Corbet
2018-11-27 19:50   ` Pavel Machek
2018-11-28 16:56     ` Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 02/13] ktask: multithread CPU-intensive kernel work Daniel Jordan
2018-11-05 20:51   ` Randy Dunlap
2018-11-06  2:24     ` Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 03/13] ktask: add undo support Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 04/13] ktask: run helper threads at MAX_NICE Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 05/13] workqueue, ktask: renice helper threads to prevent starvation Daniel Jordan
2018-11-13 16:34   ` Tejun Heo
2018-11-19 16:45     ` Daniel Jordan
2018-11-20 16:33       ` Tejun Heo
2018-11-20 17:03         ` Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 06/13] vfio: parallelize vfio_pin_map_dma Daniel Jordan
2018-11-05 21:51   ` Alex Williamson
2018-11-06  2:42     ` Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 07/13] mm: change locked_vm's type from unsigned long to atomic_long_t Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 08/13] vfio: remove unnecessary mmap_sem writer acquisition around locked_vm Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 09/13] vfio: relieve mmap_sem reader cacheline bouncing by holding it longer Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 10/13] mm: enlarge type of offset argument in mem_map_offset and mem_map_next Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 11/13] mm: parallelize deferred struct page initialization within each node Daniel Jordan
2018-11-10  3:48   ` Elliott, Robert (Persistent Memory)
2018-11-12 16:54     ` Daniel Jordan
2018-11-12 22:15       ` Elliott, Robert (Persistent Memory)
2018-11-19 16:01         ` Daniel Jordan
2018-11-27  0:12           ` Elliott, Robert (Persistent Memory)
2018-11-27 20:23             ` Daniel Jordan
2018-11-19 16:29       ` Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 12/13] mm: parallelize clear_gigantic_page Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 13/13] hugetlbfs: parallelize hugetlbfs_fallocate with ktask Daniel Jordan
2018-11-05 17:29 ` [RFC PATCH v4 00/13] ktask: multithread CPU-intensive kernel work Michal Hocko
2018-11-06  1:29   ` Daniel Jordan
2018-11-06  9:21     ` Michal Hocko
2018-11-07 20:17       ` Daniel Jordan
2018-11-05 18:49 ` Zi Yan
2018-11-06  2:20   ` Daniel Jordan
2018-11-06  2:48     ` Zi Yan
2018-11-06 19:00       ` Daniel Jordan
2018-11-30 19:18 ` Tejun Heo
2018-12-01  0:13   ` Daniel Jordan
2018-12-03 16:16     ` Tejun Heo

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