From: Andrew Morton <akpm@linux-foundation.org>
To: Ilias Stamatis <ilstam@amazon.com>
Cc: <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
<david@kernel.org>, <nadav.amit@gmail.com>,
<huang.ying.caritas@gmail.com>,
<andriy.shevchenko@linux.intel.com>, <bhe@redhat.com>,
<nh-open-source@amazon.com>
Subject: Re: [PATCH] Reinstate "resource: avoid unnecessary lookups in find_next_iomem_res()"
Date: Mon, 24 Nov 2025 08:58:16 -0800 [thread overview]
Message-ID: <20251124085816.07dbf5a4ec6235b2943840a0@linux-foundation.org> (raw)
In-Reply-To: <20251124165349.3377826-1-ilstam@amazon.com>
On Mon, 24 Nov 2025 16:53:49 +0000 Ilias Stamatis <ilstam@amazon.com> wrote:
> Commit 97523a4edb7b ("kernel/resource: remove first_lvl / siblings_only
> logic") removed an optimization introduced by commit 756398750e11
> ("resource: avoid unnecessary lookups in find_next_iomem_res()"). That
> was not called out in the message of the first commit explicitly so it's
> not entirely clear whether removing the optimization happened
> inadvertently or not.
>
> As the original commit message of the optimization explains there is no
> point considering the children of a subtree in find_next_iomem_res() if
> the top level range does not match. Reinstating the optimization results
> in significant performance improvements in systems with very large iomem
> maps when mmaping /dev/mem.
It would be great if we could quantify "significant performance
improvements"?
next prev parent reply other threads:[~2025-11-24 16:58 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-24 16:53 Ilias Stamatis
2025-11-24 16:58 ` Andrew Morton [this message]
2025-11-24 17:05 ` Andy Shevchenko
2025-11-24 18:01 ` Stamatis, Ilias
2025-11-24 18:55 ` andriy.shevchenko
2025-11-24 19:35 ` Stamatis, Ilias
2025-11-24 19:52 ` andriy.shevchenko
2025-11-24 23:30 ` Stamatis, Ilias
2025-11-25 6:50 ` andriy.shevchenko
2025-11-25 9:56 ` Stamatis, Ilias
2025-11-25 10:23 ` andriy.shevchenko
2025-11-25 14:23 ` Stamatis, Ilias
2025-11-25 18:30 ` andriy.shevchenko
2025-11-25 8:09 ` David Hildenbrand (Red Hat)
2025-11-25 8:18 ` David Hildenbrand (Red Hat)
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