From: Jason Gunthorpe <jgg@nvidia.com>
To: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Alex Williamson <alex.williamson@redhat.com>,
Alexander Duyck <alexanderduyck@fb.com>,
Andrew Morton <akpm@linux-foundation.org>,
Ben Segall <bsegall@google.com>,
Cornelia Huck <cohuck@redhat.com>,
Dan Williams <dan.j.williams@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Ingo Molnar <mingo@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Josh Triplett <josh@joshtriplett.org>,
Michal Hocko <mhocko@suse.com>, Nico Pache <npache@redhat.com>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
Peter Zijlstra <peterz@infradead.org>,
Steffen Klassert <steffen.klassert@secunet.com>,
Steve Sistare <steven.sistare@oracle.com>,
Tejun Heo <tj@kernel.org>, Tim Chen <tim.c.chen@linux.intel.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
linux-mm@kvack.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org
Subject: Re: [RFC 08/16] vfio/type1: Cache locked_vm to ease mmap_lock contention
Date: Fri, 7 Jan 2022 11:18:07 -0400 [thread overview]
Message-ID: <20220107151807.GT2328285@nvidia.com> (raw)
In-Reply-To: <20220107030642.re2d7gkfndbtzb6v@oracle.com>
On Thu, Jan 06, 2022 at 10:06:42PM -0500, Daniel Jordan wrote:
> > At least it seems like it is not an insurmountable problem if it makes
> > an appreciable difference..
>
> Ok, I can think more about this.
Unfortunately iommufd is not quite ready yet, otherwise I might
suggest just focus on that not type 1 optimizations. Depends on your
timeframe I suppose.
> > After seeing Daniels's patches I've been wondering if the pin step in
> > iommufd's draft could be parallized on a per-map basis without too
> > much trouble. It might give Daniel a way to do a quick approach
> > comparison..
>
> Sorry, comparison between what? I can take a look at iommufd tomorrow
> though and see if your comment makes more sense.
I think it might be easier to change the iommufd locking than the
type1 locking to allow kernel-side parallel map ioctls. It is already
almost properly locked for this right now, just the iopt lock covers a
little bit too much.
It could give some idea what kind of performance user managed
concurrency gives vs kernel auto threading.
Jason
next prev parent reply other threads:[~2022-01-07 15:18 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-06 0:46 [RFC 00/16] padata, vfio, sched: Multithreaded VFIO page pinning Daniel Jordan
2022-01-06 0:46 ` [RFC 01/16] padata: Remove __init from multithreading functions Daniel Jordan
2022-01-06 0:46 ` [RFC 02/16] padata: Return first error from a job Daniel Jordan
2022-01-06 0:46 ` [RFC 03/16] padata: Add undo support Daniel Jordan
2022-01-06 0:46 ` [RFC 04/16] padata: Detect deadlocks between main and helper threads Daniel Jordan
2022-01-06 0:46 ` [RFC 05/16] vfio/type1: Pass mm to vfio_pin_pages_remote() Daniel Jordan
2022-01-06 0:46 ` [RFC 06/16] vfio/type1: Refactor dma map removal Daniel Jordan
2022-01-06 0:46 ` [RFC 07/16] vfio/type1: Parallelize vfio_pin_map_dma() Daniel Jordan
2022-01-06 0:46 ` [RFC 08/16] vfio/type1: Cache locked_vm to ease mmap_lock contention Daniel Jordan
2022-01-06 0:53 ` Jason Gunthorpe
2022-01-06 1:17 ` Daniel Jordan
2022-01-06 12:34 ` Jason Gunthorpe
2022-01-06 21:05 ` Alex Williamson
2022-01-07 0:19 ` Jason Gunthorpe
2022-01-07 3:06 ` Daniel Jordan
2022-01-07 15:18 ` Jason Gunthorpe [this message]
2022-01-07 16:39 ` Daniel Jordan
2022-01-06 0:46 ` [RFC 09/16] padata: Use kthreads in do_multithreaded Daniel Jordan
2022-01-06 0:46 ` [RFC 10/16] padata: Helpers should respect main thread's CPU affinity Daniel Jordan
2022-01-06 0:46 ` [RFC 11/16] padata: Cap helpers started to online CPUs Daniel Jordan
2022-01-06 0:46 ` [RFC 12/16] sched, padata: Bound max threads with max_cfs_bandwidth_cpus() Daniel Jordan
2022-01-06 0:46 ` [RFC 13/16] padata: Run helper threads at MAX_NICE Daniel Jordan
2022-01-06 0:46 ` [RFC 14/16] padata: Nice helper threads one by one to prevent starvation Daniel Jordan
2022-01-06 0:46 ` [RFC 15/16] sched/fair: Account kthread runtime debt for CFS bandwidth Daniel Jordan
2022-01-11 11:58 ` Peter Zijlstra
2022-01-11 16:29 ` Daniel Jordan
2022-01-12 20:18 ` Tejun Heo
2022-01-13 21:08 ` Daniel Jordan
2022-01-13 21:11 ` Daniel Jordan
2022-01-14 9:31 ` Peter Zijlstra
2022-01-14 9:40 ` Peter Zijlstra
2022-01-14 16:38 ` Tejun Heo
2022-01-18 17:40 ` Daniel Jordan
2022-01-14 16:30 ` Tejun Heo
2022-01-18 17:32 ` Daniel Jordan
2022-01-06 0:46 ` [RFC 16/16] sched/fair: Consider kthread debt in cputime Daniel Jordan
2022-01-06 1:13 ` [RFC 00/16] padata, vfio, sched: Multithreaded VFIO page pinning Jason Gunthorpe
2022-01-07 3:03 ` Daniel Jordan
2022-01-07 17:12 ` Jason Gunthorpe
2022-01-10 22:27 ` Daniel Jordan
2022-01-11 0:17 ` Jason Gunthorpe
2022-01-11 16:20 ` Daniel Jordan
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