From: Andrew Morton <akpm@linux-foundation.org>
To: Scott Cheloha <cheloha@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org,
"Rafael J. Wysocki" <rafael@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
David Hildenbrand <david@redhat.com>,
nathanl@linux.ibm.com, ricklind@linux.vnet.ibm.com,
mhocko@suse.com, Scott Cheloha <cheloha@linux.ibm.com>
Subject: Re: [PATCH v4] drivers/base/memory.c: cache blocks in radix tree to accelerate lookup
Date: Thu, 9 Jan 2020 14:00:04 -0800 [thread overview]
Message-ID: <20200109140004.d5e6dc581b62d6e078dcca4c@linux-foundation.org> (raw)
In-Reply-To: <20200109212516.17849-1-cheloha@linux.vnet.ibm.com>
On Thu, 9 Jan 2020 15:25:16 -0600 Scott Cheloha <cheloha@linux.vnet.ibm.com> wrote:
> Searching for a particular memory block by id is an O(n) operation
> because each memory block's underlying device is kept in an unsorted
> linked list on the subsystem bus.
>
> We can cut the lookup cost to O(log n) if we cache the memory blocks in
> a radix tree. With a radix tree cache in place both memory subsystem
> initialization and memory hotplug run palpably faster on systems with a
> large number of memory blocks.
>
> ...
>
> @@ -56,6 +57,13 @@ static struct bus_type memory_subsys = {
> .offline = memory_subsys_offline,
> };
>
> +/*
> + * Memory blocks are cached in a local radix tree to avoid
> + * a costly linear search for the corresponding device on
> + * the subsystem bus.
> + */
> +static RADIX_TREE(memory_blocks, GFP_KERNEL);
What protects this tree from racy accesses?
next prev parent reply other threads:[~2020-01-09 22:00 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20191217193238-1-cheloha@linux.vnet.ibm.com>
2020-01-09 21:19 ` [PATCH] drivers/base/memory.c: cache blocks in radix tree to accelerate lookup Scott Cheloha
2020-01-09 21:30 ` Michal Hocko
2020-01-09 21:25 ` [PATCH v4] " Scott Cheloha
2020-01-09 22:00 ` Andrew Morton [this message]
2020-01-09 22:17 ` David Hildenbrand
2020-01-09 22:27 ` Andrew Morton
2020-01-09 22:35 ` David Hildenbrand
2020-01-10 9:32 ` David Hildenbrand
2020-01-10 11:31 ` Michal Hocko
2020-01-15 19:09 ` David Hildenbrand
2020-01-16 15:22 ` Michal Hocko
2020-01-16 15:28 ` David Hildenbrand
2020-01-16 16:17 ` David Hildenbrand
2020-01-17 9:35 ` Michal Hocko
2020-01-20 9:15 ` David Hildenbrand
2020-01-21 12:30 ` Michal Hocko
2020-01-16 17:17 ` Don Dutile
2020-01-21 23:10 ` [PATCH v5] drivers/base/memory.c: cache memory blocks in xarray " Scott Cheloha
2020-01-22 10:43 ` David Hildenbrand
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