From: Don Dutile <ddutile@redhat.com>
To: David Hildenbrand <david@redhat.com>, Michal Hocko <mhocko@kernel.org>
Cc: Scott Cheloha <cheloha@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org,
"Rafael J. Wysocki" <rafael@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
nathanl@linux.ibm.com, ricklind@linux.vnet.ibm.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, 16 Jan 2020 12:17:01 -0500 [thread overview]
Message-ID: <007f0eed-0d42-f0de-8af4-acae69db0a42@redhat.com> (raw)
In-Reply-To: <765a07fe-47e9-fe3d-716a-44d9ee4a5e99@redhat.com>
On 1/16/20 10:28 AM, David Hildenbrand wrote:
> On 16.01.20 16:22, Michal Hocko wrote:
>> On Wed 15-01-20 20:09:48, David Hildenbrand wrote:
>>> On 09.01.20 22:25, Scott Cheloha 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.
>>>>
>>>> Signed-off-by: Scott Cheloha <cheloha@linux.ibm.com>
>>>> Acked-by: David Hildenbrand <david@redhat.com>
>>>> Acked-by: Nathan Lynch <nathanl@linux.ibm.com>
>>>> Acked-by: Michal Hocko <mhocko@suse.com>
>>>
>>> Soooo,
>>>
>>> I just learned that radix trees are nowadays only a wrapper for xarray
>>> (for quite a while already!), and that the xarray interface shall be
>>> used in new code.
>>
>> Good point. I somehow didn't realize this would add more work for a
>> later code refactoring. The mapping should be pretty straightforward.
>
> Yes it is. @Scott, care to send a fixup that does the mapping?
>
>>
>> Thanks for noticing!
>
> Don noticed it, so thanks to him :)
>
Backporting XArray to RHEL-8, and continuing to support radix-tree api in RHEL-8 due to RHEL rulz, it wasn't stable/bug-free everyewhere, etc., was a challenge, thus my 'sensitivity' to seeing new radix-tree code upstream.
>
next prev parent reply other threads:[~2020-01-16 17:20 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
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 [this message]
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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