From: Joerg Roedel <jroedel@suse.de>
To: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Oded Gabbay <oded.gabbay@amd.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] mm: export find_extend_vma and handle_mm_fault for driver use
Date: Thu, 6 Nov 2014 14:01:22 +0100 [thread overview]
Message-ID: <20141106130122.GJ8354@suse.de> (raw)
In-Reply-To: <20141105135109.39ea54fe@jbarnes-hsw>
On Wed, Nov 05, 2014 at 01:51:09PM -0800, Jesse Barnes wrote:
> On Wed, 5 Nov 2014 13:03:51 +0100
> Joerg Roedel <jroedel@suse.de> wrote:
> > Thanks for testing Oded. Jesse, the patch looks good to me, except the
> > task accounting for the page-faults. I'd like to get rid of using
> > task_struct in the IOMMUv2 driver entirely if possible. Also it is not
> > really the CPU task causing the faults, but some non-CPU process.
>
> Hm, but the CPU task initiates the activity on the GPU, so we should
> account for it somewhere, right? I guess I had been thinking of the
> "task" as spanning the CPUs and GPUs and other devices in the system,
> rather than just representing the CPU activity.
One problem is that the task that called amd_iommu_bind_pasid() isn't
necessarily the same task (thread) that queues the jobs to the device.
The thread that called amd_iommu_bind_pasid() might even exit while
other threads still use the mappings.
Besides that, from an abstract point of view, what is running on the
device (GPU) is a logically seperate 'thread' of the process which we
should account for seperatly. If we want accounting for these off-CPU
threads we should probably introduce some concept of a non-CPU task to
the kernel and do the accounting there?
Joerg
next prev parent reply other threads:[~2014-11-06 13:01 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-24 19:34 [PATCH 1/2] mm: export find_extend_vma and handle_mm_fault for driver use Jesse Barnes
2014-10-24 19:34 ` [PATCH 2/2] iommu/amd: use handle_mm_fault directly Jesse Barnes
2014-10-27 15:13 ` [PATCH 1/2] mm: export find_extend_vma and handle_mm_fault for driver use Joerg Roedel
2014-10-27 15:15 ` Oded Gabbay
2014-10-27 15:35 ` Jesse Barnes
2014-10-27 15:37 ` Oded Gabbay
2014-10-29 9:33 ` Oded Gabbay
2014-10-29 14:37 ` Jesse Barnes
2014-11-05 12:03 ` Joerg Roedel
2014-11-05 21:51 ` Jesse Barnes
2014-11-06 8:51 ` Oded Gabbay
2014-11-06 13:03 ` Joerg Roedel
2014-11-06 13:01 ` Joerg Roedel [this message]
2014-11-12 22:07 ` Jesse Barnes
2014-11-17 16:53 ` Joerg Roedel
2014-11-12 22:10 Jesse Barnes
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