From: Boris Brezillon <boris.brezillon@collabora.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: "Christian A. Ehrhardt" <lk@c--e.de>,
dri-devel@lists.freedesktop.org,
Steven Price <steven.price@arm.com>,
Liviu Dudau <liviu.dudau@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Maxime Ripard <mripard@kernel.org>,
Thomas Zimmermann <tzimmermann@suse.de>,
David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/panthor: Check VMA boundaries for PMD mappings
Date: Tue, 23 Jun 2026 22:44:21 +0200 [thread overview]
Message-ID: <20260623224421.56dba65d@fedora-2.home> (raw)
In-Reply-To: <20260623220341.7ad4a0e2@fedora-2.home>
On Tue, 23 Jun 2026 22:03:41 +0200
Boris Brezillon <boris.brezillon@collabora.com> wrote:
> Anyway, I'll try to get back to this map_pages() implementation, and
> see how we can handle the fallback when locks can't be acquired in that
> path (I assume this would mean no PMD mapping in the fallback path if
> we get rid of huge_fault()).
More on that. I had a brief look at map_pages()/fault_around(), and it
seems it's only meant to populate PTE entries, not PMDs. Part of the
perf boost we were looking for when adding huge_fault() was limiting
the number of faults when adjacent pages are touched, but the other
part was limiting the page table depth to optimize page-table walks, so
if we're implementing map_pages() without huge_fault(), we basically
lose the second part of the optimization. I'd need to check how much
perf we leave on the table with that.
prev parent reply other threads:[~2026-06-23 20:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-23 18:19 [PATCH] drm/panthor: Check VMA boundaries for PMD mappings Christian A. Ehrhardt
2026-06-23 18:33 ` Matthew Wilcox
2026-06-23 20:03 ` Boris Brezillon
2026-06-23 20:44 ` Boris Brezillon [this message]
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