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From: Shakeel Butt <shakeel.butt@linux.dev>
To: Kairui Song <ryncsn@gmail.com>
Cc: kasong@tencent.com, linux-mm@kvack.org, 
	Andrew Morton <akpm@linux-foundation.org>, Axel Rasmussen <axelrasmussen@google.com>, 
	Yuanchu Xie <yuanchu@google.com>, Wei Xu <weixugc@google.com>, 
	Johannes Weiner <hannes@cmpxchg.org>, David Hildenbrand <david@kernel.org>, 
	Michal Hocko <mhocko@kernel.org>, Qi Zheng <zhengqi.arch@bytedance.com>, 
	Lorenzo Stoakes <ljs@kernel.org>, Barry Song <baohua@kernel.org>, 
	David Stevens <stevensd@google.com>, Chen Ridong <chenridong@huaweicloud.com>, 
	Leno Hou <lenohou@gmail.com>, Yafang Shao <laoar.shao@gmail.com>, Yu Zhao <yuzhao@google.com>, 
	Zicheng Wang <wangzicheng@honor.com>, Kalesh Singh <kaleshsingh@google.com>, 
	Suren Baghdasaryan <surenb@google.com>, Chris Li <chrisl@kernel.org>, Vernon Yang <vernon2gm@gmail.com>, 
	linux-kernel@vger.kernel.org, Qi Zheng <qi.zheng@linux.dev>, 
	Baolin Wang <baolin.wang@linux.alibaba.com>
Subject: Re: [PATCH v2 12/12] mm/vmscan: unify writeback reclaim statistic
 and throttling
Message-ID: <ac3fg6LpRCKEpoJv@linux.dev>
References: <20260329-mglru-reclaim-v2-0-b53a3678513c@tencent.com>
 <20260329-mglru-reclaim-v2-12-b53a3678513c@tencent.com>
 <ac3VV7h1fuDuUOJA@linux.dev>
 <ac3YKAh1Kzmpwhi0@KASONG-MC4>
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In-Reply-To: <ac3YKAh1Kzmpwhi0@KASONG-MC4>
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On Thu, Apr 02, 2026 at 10:56:07AM +0800, Kairui Song wrote:
> On Wed, Apr 01, 2026 at 07:39:03PM +0800, Shakeel Butt wrote:
> > On Sun, Mar 29, 2026 at 03:52:38AM +0800, Kairui Song via B4 Relay wrote:
> > > From: Kairui Song <kasong@tencent.com>
> > > 
[...]
> > > 
> > > After this commit, congestion control is now effective and no more
> > 
> > What do you mean by congestion control here?
> 
> This particular case demostrated here is VMSCAN_THROTTLE_CONGESTED so
> I described it as "congestion control", may I'll just say throttling to
> avoid confusion, it's not limited to that.

Yes use throttling or VMSCAN_THROTTLE_CONGESTED directly. Congestion control
gives a networking vibe.

> 
> > 
> > > spin on LRU or premature OOM.
> > > 
> > > Stress test on other workloads also looking good.
> > > 
> > > Suggested-by: Chen Ridong <chenridong@huaweicloud.com>
> > > Signed-off-by: Kairui Song <kasong@tencent.com>
> > 
> > There is still differences for global and kswapd reclaim in the shrink_node()
> > like kswapd throttling and congestion state management and throttling. Any plan
> > to unify them?
> 
> Of course. Let fix it step by step,

Fine with me but better to be clear about the destination.

> this series is pretty long already.
> I originally plan to put this patch in a later series, but as Ridong
> pointed out leaving these counter updated but unused looks really
> ugly. And this fix is clean and easily to understand I think.