Re: [PATCH] vfs: keep inodes with page cache off the inode shrinker LRU

From: santosh.shilimkar@oracle.com
To: Nishanth Menon <nm@ti.com>
Cc: Arnd Bergmann <arnd@arndb.de>, Tero Kristo <t-kristo@ti.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Michal Hocko <mhocko@suse.com>, Rik van Riel <riel@surriel.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Santosh Shilimkar <ssantosh@kernel.org>,
	Dave Chinner <david@fromorbit.com>,
	Russell King - ARM Linux admin <linux@armlinux.org.uk>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>, Yafang Shao <laoar.shao@gmail.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Johannes Weiner <hannes@cmpxchg.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	kernel-team@fb.com, Kishon Vijay Abraham I <kishon@ti.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Roman Gushchin <guro@fb.com>
Subject: Re: [PATCH] vfs: keep inodes with page cache off the inode shrinker LRU
Date: Fri, 6 Mar 2020 17:08:03 -0800	[thread overview]
Message-ID: <7b179d51-3d08-53f5-9b6e-552869f8ed78@oracle.com> (raw)
In-Reply-To: <20200306203439.peytghdqragjfhdx@kahuna>


On 3/6/20 12:34 PM, Nishanth Menon wrote:
> On 13:11-20200226, santosh.shilimkar@oracle.com wrote:
>> +Nishant, Tero
>>
>> On 2/26/20 1:01 PM, Arnd Bergmann wrote:
>>> On Wed, Feb 26, 2020 at 7:04 PM <santosh.shilimkar@oracle.com> wrote:
>>>>
>>>> On 2/13/20 8:52 AM, Arnd Bergmann wrote:
>>>>> On Wed, Feb 12, 2020 at 9:50 AM Russell King - ARM Linux admin
>>>>> <linux@armlinux.org.uk> wrote:
>>>>
>>>> The Keystone generations of SOCs have been used in different areas and
>>>> they will be used for long unless says otherwise.
>>>>
>>>> Apart from just split of lowmem and highmem, one of the peculiar thing
>>>> with Keystome family of SOCs is the DDR is addressable from two
>>>> addressing ranges. The lowmem address range is actually non-cached
>>>> range and the higher range is the cacheable.
>>>
>>> I'm aware of Keystone's special physical memory layout, but for the
>>> discussion here, this is actually irrelevant for the discussion about
>>> highmem here, which is only about the way we map all or part of the
>>> available physical memory into the 4GB of virtual address space.
>>>
>>> The far more important question is how much memory any users
>>> (in particular the subset that are going to update their kernels
>>> several years from now) actually have installed. Keystone-II is
>>> one of the rare 32-bit chips with fairly wide memory interfaces,
>>> having two 72-bit (with ECC) channels rather than the usual one
>>>    or two channels of 32-bit DDR3. This means a relatively cheap
>>> 4GB configuration using eight 256Mx16 chips is possible, or
>>> even a 8GB using sixteen or eighteen 512Mx8.
>>>
>>> Do you have an estimate on how common these 4GB and 8GB
>>> configurations are in practice outside of the TI evaluation
>>> board?
>>>
>>  From my TI memories, many K2 customers were going to install
>> more than 2G memory. Don't remember 8G, but 4G was the dominant
>> one afair. Will let Nishant/Tero elaborate latest on this.
>>
> 
> Thanks for the headsup, it took a little to dig up the current
> situation:
> 
> ~few 1000s still relevant spread between 4G and 8G (confirmed that both
> are present, relevant and in use).
> 
> I wish we could sunset, but unfortunately, I am told(and agree)
> that we should'nt just leave products (and these are long term
> products stuck in critical parts in our world) hanging in the air, and
> migrations to newer kernel do still take place periodically (the best
> I can talk in public forum at least).
> 
Thanks Nishant !!