From: Gregory Price <gregory.price@memverge.com>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Gregory Price <gourry.memverge@gmail.com>,
linux-mm@kvack.org, linux-doc@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-api@vger.kernel.org, x86@kernel.org,
akpm@linux-foundation.org, arnd@arndb.de, tglx@linutronix.de,
luto@kernel.org, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, hpa@zytor.com, mhocko@kernel.org,
tj@kernel.org, corbet@lwn.net, rakie.kim@sk.com,
hyeongtak.ji@sk.com, honggyu.kim@sk.com, vtavarespetr@micron.com,
peterz@infradead.org, jgroves@micron.com,
ravis.opensrc@micron.com, sthanneeru@micron.com,
emirakhur@micron.com, Hasan.Maruf@amd.com,
seungjun.ha@samsung.com
Subject: Re: [PATCH v5 01/11] mm/mempolicy: implement the sysfs-based weighted_interleave interface
Date: Tue, 2 Jan 2024 21:46:38 -0500 [thread overview]
Message-ID: <ZZTKjn3kngYPYXo0@memverge.com> (raw)
In-Reply-To: <87h6jwdvxn.fsf@yhuang6-desk2.ccr.corp.intel.com>
On Tue, Jan 02, 2024 at 03:41:08PM +0800, Huang, Ying wrote:
> Think about the default weight value via HMAT/CDAT again. It may be not
> a good idea to use "1" as default even for now.
>
> For example,
>
> - The memory bandwidth of DRAM is 100GB, whose default weight is "1".
>
> - We hot-plug CXL.mem A with memory bandwidth 20GB. So, we change the
> weight of DRAM to 5, and use "1" as the weight of CXL.mem A.
>
> - We hot-plug CXL.mem B with memory bandwidth 10GB. So, we change the
> weight of DRAM to 10, the weight of CXL.mem A to 2, and use "1" as the
> weight of CXL.mem B.
>
> That is, if we use "1" as default weight, we need to change weights of
> nodes frequently because we haven't a "base" weight. The best candidate
> base weight is the weight of DRAM node. For example, if we set the
> default weight of DRAM node to be "16" and use that as the base weight,
> we don't need to change it in most cases. The weight of other nodes can
> be set according to the ratio of its memory bandwidth to that of DRAM.
>
> This makes it easy to set the default weight via HMAT/CDAT too.
>
> What do you think about that?
>
Giving this more thought.
Hotplug should be an incredibly rare event. I don't think swapping defaults
"frequently" is a real problem we should handle.
It's expected that dynamic capacity devices will not cause a node to
hotplug, but instead cause a node to grow/shrink.
Seems perfectly fine to rebalance weights in response to rare events.
~Gregory
next prev parent reply other threads:[~2024-01-03 2:46 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-23 18:10 [PATCH v5 00/11] mempolicy2, mbind2, and weighted interleave Gregory Price
2023-12-23 18:10 ` [PATCH v5 01/11] mm/mempolicy: implement the sysfs-based weighted_interleave interface Gregory Price
2023-12-27 6:42 ` Huang, Ying
2023-12-26 6:48 ` Gregory Price
2024-01-02 7:41 ` Huang, Ying
2024-01-02 19:45 ` Gregory Price
2024-01-03 2:45 ` Huang, Ying
2024-01-03 2:59 ` Gregory Price
2024-01-03 6:03 ` Huang, Ying
2024-01-03 2:46 ` Gregory Price [this message]
2023-12-23 18:10 ` [PATCH v5 02/11] mm/mempolicy: introduce MPOL_WEIGHTED_INTERLEAVE for weighted interleaving Gregory Price
2023-12-27 8:32 ` Huang, Ying
2023-12-26 7:01 ` Gregory Price
2023-12-26 8:06 ` Gregory Price
2023-12-26 11:32 ` Gregory Price
2024-01-02 8:42 ` Huang, Ying
2024-01-02 20:30 ` Gregory Price
2024-01-03 5:46 ` Huang, Ying
2024-01-03 22:09 ` Gregory Price
2024-01-04 5:39 ` Huang, Ying
2024-01-04 18:59 ` Gregory Price
2024-01-05 6:51 ` Huang, Ying
2024-01-05 7:25 ` Gregory Price
2024-01-08 7:08 ` Huang, Ying
2023-12-23 18:10 ` [PATCH v5 03/11] mm/mempolicy: refactor sanitize_mpol_flags for reuse Gregory Price
2023-12-27 8:39 ` Huang, Ying
2023-12-26 7:05 ` Gregory Price
2023-12-26 11:48 ` Gregory Price
2024-01-02 9:09 ` Huang, Ying
2024-01-02 20:32 ` Gregory Price
2023-12-23 18:10 ` [PATCH v5 04/11] mm/mempolicy: create struct mempolicy_args for creating new mempolicies Gregory Price
2023-12-23 18:10 ` [PATCH v5 05/11] mm/mempolicy: refactor kernel_get_mempolicy for code re-use Gregory Price
2023-12-23 18:10 ` [PATCH v5 06/11] mm/mempolicy: allow home_node to be set by mpol_new Gregory Price
2023-12-23 18:10 ` [PATCH v5 07/11] mm/mempolicy: add userland mempolicy arg structure Gregory Price
2023-12-23 18:10 ` [PATCH v5 08/11] mm/mempolicy: add set_mempolicy2 syscall Gregory Price
2024-01-02 14:38 ` Geert Uytterhoeven
2023-12-23 18:10 ` [PATCH v5 09/11] mm/mempolicy: add get_mempolicy2 syscall Gregory Price
2024-01-02 14:46 ` Geert Uytterhoeven
2023-12-23 18:11 ` [PATCH v5 10/11] mm/mempolicy: add the mbind2 syscall Gregory Price
2024-01-02 14:47 ` Geert Uytterhoeven
2023-12-23 18:11 ` [PATCH v5 11/11] mm/mempolicy: extend set_mempolicy2 and mbind2 to support weighted interleave Gregory Price
2023-12-25 7:54 ` [PATCH v5 00/11] mempolicy2, mbind2, and " Huang, Ying
2023-12-26 7:45 ` Gregory Price
2024-01-02 4:27 ` Huang, Ying
2024-01-02 19:06 ` Gregory Price
2024-01-03 3:15 ` Huang, Ying
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZZTKjn3kngYPYXo0@memverge.com \
--to=gregory.price@memverge.com \
--cc=Hasan.Maruf@amd.com \
--cc=akpm@linux-foundation.org \
--cc=arnd@arndb.de \
--cc=bp@alien8.de \
--cc=corbet@lwn.net \
--cc=dave.hansen@linux.intel.com \
--cc=emirakhur@micron.com \
--cc=gourry.memverge@gmail.com \
--cc=honggyu.kim@sk.com \
--cc=hpa@zytor.com \
--cc=hyeongtak.ji@sk.com \
--cc=jgroves@micron.com \
--cc=linux-api@vger.kernel.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=luto@kernel.org \
--cc=mhocko@kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=rakie.kim@sk.com \
--cc=ravis.opensrc@micron.com \
--cc=seungjun.ha@samsung.com \
--cc=sthanneeru@micron.com \
--cc=tglx@linutronix.de \
--cc=tj@kernel.org \
--cc=vtavarespetr@micron.com \
--cc=x86@kernel.org \
--cc=ying.huang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).