mails/lsfmm_2024: Wordsmith and update

Signed-off-by: SeongJae Park <sj@kernel.org>

1 files changed, 54 insertions, 42 deletions

diff --git a/mails/lsfmm_2024 b/mails/lsfmm_2024
index 188009d..d8f71ff 100644
--- a/mails/lsfmm_2024
+++ b/mails/lsfmm_2024
@@ -4,78 +4,90 @@ Cc: damon@lists.linux.dev
 Cc: linux-mm@kvack.org
 Cc: linux-kernel@vger.kernel.org
 Cc: sj@kernel.org
-Subject: [LSF/MM/BPF TOPIC] DAMON Updates and Plans: DAMOS Self-tuning and Access/Contiguity-aware Memory Auto-scaling
+Subject: [LSF/MM/BPF TOPIC] DAMON Updates and Plans: Automation of DAMON tuning, tiering, and VM guest scaling
 
 Hi all,
 
 
-Thanks to the discussions and feedback we received last year from the
+Thanks to the discussions and feedback that we received last year from the
 LSF/MM/BPF 2023's DAMON updates and future plans session[1], DAMON made many
 advances and yet more future plans.  I'd like to again share/discuss the
 followup changes and status we made so far after the last year's session, and
-the future development plans in the LSF/MM/BPF 2024.
+the future development plans on LSF/MM/BPF 2024.
 
-Among the detailed topics, most important topics that I'd like to share and
-discuss are below.
+A few topics would be shared, including below.
 
 User Aims-oriented DAMOS Self-tuning
 ------------------------------------
 
 I shared "feedback-based quota auto tuning" as the top priority item for 2023
-on last year's session.  Fortunately it made some progress.  As of this
-writing, the feedback loop algorithm, user feedback interface, and integration
-of the two parts are implemented and merged in the mm tree.  By the time of
-LSF/MM/BPF 2024, hopefully the remaining part of the initial idea, specifically
-making DAMON feeds itself, will be implemented and merged in the mm tree.
-
-I'd like to share the implementation detail and discuss about remaining rooms
-for improvements and find future extension opportunities including tiered
-memory management and general NUMA balancing.  Particularly the tiered memory
-management could be the main topic for the future opportunity.  We shared a
-detailed RFC idea[2] of it based on the self-tuning a couple of months ago.
-Recently SK hynix has also adopted DAMON for their CXL-based tiered memory
-management solution[3].  Updates on the ideas, collaboration results, and
-hopefully early proof-of-concepts level implementation maybe shared on the
-session.
+in last year's session.  Fortunately it made some progress.  A simple feedback
+loop-based quota tuning and user feedback interface have been implemented and
+merged into the mainline from v6.8-rc1.  By the time of LSF/MM/BPF 2024,
+hopefully the remaining part of the initial idea, specifically making DAMON
+feeds itself, will be implemented and merged in the mm tree.
+
+I'd like to share the implementation details, discuss remaining rooms for
+improvements, and find future extension opportunities.  Hopefully DAMON
+monitoring parameters auto-tuning would be one of the future works to consider.
+
+DAMON-based Tiered Memory Management
+------------------------------------
+
+I'm personally not working on this topic directly, but apparently a few folks
+are exploring DAMON usage for tiered memory management.  Some academic
+papers[2,3] exploring the opportunity have been published.   I shared a rough
+RFC idea[4] of it based on the self-tuning in November 2023.  Recently SK hynix
+has also adopted DAMON for their CXL-based tiered memory management
+solution[5], and sent patches for their work[6].
+
+I'd like to provide a summary of the ongoing works and updates on my idea.
+Hopefully early proof-of-concepts level implementation of my idea would be
+shared in the session.
 
 Access/Contiguity-aware Memory Auto-scaling
 -------------------------------------------
 
-This is a new idea which was not discussed in last year's LSF/MM/BPF.  The idea
-is for improving free pages reporting-based memory over-subscribed VM systems.
-Specifically, it will steal guest memory based on access pattern in
-contiguity-aware manner and report those to the host.  Further, it will
-pseudo-hotunplug completely stolen memory blocks to reduce 'struct page'
-overhead.  Expected benefit is simplification of the guest's kernel control and
-more reliable/successful management of host-reusable pages.  More detailed
-idea[4] has shared before.
-
-Because it is still in pure idea level, no many progress until LSF/MM/BPF is
+This is a new idea which was not discussed in last year's LSF/MM/BPF.  The main
+purpose is to implement an access-aware, efficient, reliable, and simple to use
+memory over-subscribed VM guest kernels.  Specifically, it will steal guest
+memory based on access patterns in a contiguity-aware manner and report those
+to the host as free to use.  The PSI-based stealing aggressiveness auto-tuning
+may be used.  It will also apply a 'struct page' overhead reduction mechanism
+to the stolen memory.  We're currently thinking about memory hotplugging and
+vmemmap remapping as candidate mechanisms.  For simple usage, the interface
+will be similar to that of virtio-balloon, which is widely adopted.  The first
+version of the more detailed idea[7] has been shared before.
+
+Because it is still at a pure idea level, not much progress until LSF/MM/BPF is
 expected.  This item would be primarily for the future plans part.  That said,
-hopefully early proof-of-concepts level impelmentation or some test results
-will be shared.  Since this is expected to be more for future plans than status
-update, I hope to have more discussions for getting design level concerns and
-possible collaboration chances.
+at least a second version of the design will be shared before.  Also hopefully
+early proof-of-concepts level implementation or some test results will be
+shared.  Since this is expected to be more for future plans than status update,
+I hope to have more discussions for getting design level concerns and possible
+collaboration chances.
 
 Misc
 ----
 
-If time allows, I would be able to cover more followups for items that I shared
-as the future plans, and the feedback/questions I received from the last year's
-session.
+If time allows, I would be able to cover more follow ups for items that I
+shared as the future plans, and the feedback/questions I received from the last
+year's session.
 
 - Merging DAMON user-space tool in the tree
+- DAMON documentation improvements
 - Write-only monitoring
 - THP memory footprint reduction
 - DAMON-based working set size report
-- DAMON_RECLAIM control via virtio-balloon with free pages reporting
-- documentation
 - In production DAMON usages
 
 [1] https://lwn.net/Articles/931769/
-[2] https://lore.kernel.org/damon/20231112195602.61525-1-sj@kernel.org/
-[3] https://github.com/skhynix/hmsdk/releases/tag/hmsdk-v2.0
-[4] https://lore.kernel.org/damon/20231112195114.61474-1-sj@kernel.org/
+[2] https://arxiv.org/abs/2302.09468
+[3] https://dl.acm.org/doi/10.1145/3600006.3613167
+[4] https://lore.kernel.org/damon/20231112195602.61525-1-sj@kernel.org/
+[5] https://github.com/skhynix/hmsdk/releases/tag/hmsdk-v2.0
+[6] https://lore.kernel.org/r/20240115045253.1775-1-honggyu.kim@sk.com
+[7] https://lore.kernel.org/damon/20231112195114.61474-1-sj@kernel.org/
 
 
 Thanks,