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[109.81.94.251]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-42caeb32318sm66714455e9.17.2024.09.09.00.12.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Sep 2024 00:12:04 -0700 (PDT) Date: Mon, 9 Sep 2024 09:12:03 +0200 From: Michal Hocko To: Hillf Danton Cc: Davidlohr Bueso , yosryahmed@google.com, Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH -next] mm: introduce per-node proactive reclaim interface Message-ID: References: <20240906110419.2079-1-hdanton@sina.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240906110419.2079-1-hdanton@sina.com> On Fri 06-09-24 19:04:19, Hillf Danton wrote: > On Thu, 5 Sep 2024 16:29:41 -0700 Davidlohr Bueso > > On Fri, 06 Sep 2024, Hillf Danton wrote:\n > > >The proactive reclaim on the cmdline looks like waste of cpu cycles before > > >the cases where kswapd fails to work are spotted. It is not correct to add > > >it because you can type the code. > > > > Are you against proactive reclaim altogether (ie: memcg) or this patch in > > particular, which extends its availability? > > > The against makes no sense to me because I know your patch is never able to > escape standing ovation. I fail to understand your reasoning. Do you have any actual technical arguments why this is a bad idea? > > The benefits of proactive reclaim are well documented, and the community has > > been overall favorable towards it. This operation is not meant to be generally > > used, but there are real latency benefits to be had which are completely > > unrelated to watermarks. Similarly, we have 'compact' as an alternative to > > kcompactd (which was once upon a time part of kswapd). > > > Because kswapd is responsible for watermark instead of high order pages, > compact does not justify proactive reclaim from the begining. What do you mean? How does keeping a global watermark helps to trigger per NUMA node specific aging - e.g. demotion? Or do you dispute the overall idea and have a different idea how to achieve those usecases? -- Michal Hocko SUSE Labs