From: "Christian König" <christian.koenig@amd.com>
To: Simon Ser <contact@emersion.fr>, Pekka Paalanen <ppaalanen@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
Szabolcs Nagy <szabolcs.nagy@arm.com>,
dri-devel@lists.freedesktop.org, Andrei Vagin <avagin@gmail.com>,
Kalesh Singh <kaleshsingh@google.com>, Hui Su <sh_def@163.com>,
Michel Lespinasse <walken@google.com>,
Jonathan Corbet <corbet@lwn.net>,
Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
Jeffrey Vander Stoep <jeffv@google.com>,
Daniel Jordan <daniel.m.jordan@oracle.com>,
kernel-team <kernel-team@android.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Linux Media Mailing List <linux-media@vger.kernel.org>,
Kees Cook <keescook@chromium.org>, Jann Horn <jannh@google.com>,
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kernel list <linux-kernel@vger.kernel.org>,
Minchan Kim <minchan@kernel.org>,
Yafang Shao <laoar.shao@gmail.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
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Hridya Valsaraju <hridya@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linux API <linux-api@vger.kernel.org>
Subject: Re: [PATCH] procfs/dmabuf: Add /proc/<pid>/task/<tid>/dmabuf_fds
Date: Fri, 29 Jan 2021 15:22:06 +0100 [thread overview]
Message-ID: <f680ced7-3402-4a1e-4565-35ad7cd0c46d@amd.com> (raw)
In-Reply-To: <wgUb8smQArgjbRFYMPYVDmukBT-_BrqG2M6XIOkWdBcW_x-m4ORnl3VOvH3J4wrsNGMoOXqMAro0UmkdVXFNso9PEiNCFGEeruibhWsmU34=@emersion.fr>
Am 29.01.21 um 15:17 schrieb Simon Ser:
> On Friday, January 29th, 2021 at 3:13 PM, Pekka Paalanen <ppaalanen@gmail.com> wrote:
>
>>> Re-importing it adds quite a huge CPU overhead to both userspace as well
>>> as the kernel.
>> Perhaps, but so far it seems no-one has noticed the overhead, with Mesa
>> at least.
>>
>> I happily stand corrected.
> Note, all of this doesn't mean that compositors will stop keeping
> DMA-BUF FDs around. They may want to keep them open for other purposes
> like importing them into KMS or other EGL displays as needed.
Correct and that's a perfectly valid use case. Just re-importing it on
every frame is something we should really try to avoid.
At least with debugging enabled it's massive overhead and maybe even
performance penalty when we have to re-create device page tables all the
time.
But thinking more about that it is possible that we short-cut this step
as long as the original import was still referenced. Otherwise we
probably would have noticed this much earlier.
Regards,
Christian.
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next prev parent reply other threads:[~2021-01-29 14:22 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-26 22:51 [PATCH] procfs/dmabuf: Add /proc/<pid>/task/<tid>/dmabuf_fds Kalesh Singh
2021-01-26 22:51 ` Kalesh Singh
2021-01-27 9:05 ` Michal Hocko
2021-01-27 9:05 ` Michal Hocko
2021-01-27 10:53 ` Christian König
2021-01-27 10:53 ` Christian König
2021-01-27 11:02 ` Michal Hocko
2021-01-27 11:02 ` Michal Hocko
2021-01-27 11:08 ` Christian König
2021-01-27 11:08 ` Christian König
2021-01-27 11:23 ` Michal Hocko
2021-01-27 11:23 ` Michal Hocko
2021-01-27 10:47 ` Jann Horn
2021-01-27 10:47 ` Jann Horn
2021-01-27 10:57 ` Michal Hocko
2021-01-27 10:57 ` Michal Hocko
2021-01-27 11:01 ` Christian König
2021-01-27 11:01 ` Christian König
2021-01-27 11:27 ` Michal Hocko
2021-01-27 11:27 ` Michal Hocko
2021-01-28 10:01 ` Pekka Paalanen
2021-01-28 10:01 ` Pekka Paalanen
2021-01-29 12:18 ` Christian König
2021-01-29 14:13 ` Pekka Paalanen
2021-01-29 14:17 ` Simon Ser
2021-01-29 14:22 ` Christian König [this message]
2021-02-03 10:23 ` Daniel Vetter
2021-02-03 10:23 ` Daniel Vetter
2021-01-27 17:16 ` Kalesh Singh
2021-01-27 17:16 ` Kalesh Singh
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