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[49.180.121.96]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-724de477e65sm7082459b3a.53.2024.11.25.16.51.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Nov 2024 16:51:32 -0800 (PST) Received: from dave by dread.disaster.area with local (Exim 4.98) (envelope-from ) id 1tFjnd-0000000368t-1RBT; Tue, 26 Nov 2024 11:51:29 +1100 Date: Tue, 26 Nov 2024 11:51:29 +1100 From: Dave Chinner To: Stephen Zhang Cc: djwong@kernel.org, dchinner@redhat.com, leo.lilong@huawei.com, wozizhi@huawei.com, osandov@fb.com, xiang@kernel.org, zhangjiachen.jaycee@bytedance.com, linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, zhangshida@kylinos.cn Subject: Re: [PATCH 0/5] *** Introduce new space allocation algorithm *** Message-ID: References: <20241104014439.3786609-1-zhangshida@kylinos.cn> Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Thu, Nov 21, 2024 at 03:17:04PM +0800, Stephen Zhang wrote: > Dave Chinner 于2024年11月21日周四 06:53写道： > > > > On Sun, Nov 17, 2024 at 09:34:53AM +0800, Stephen Zhang wrote: > > > Dave Chinner 于2024年11月11日周一 10:04写道： > > > > > > > > On Fri, Nov 08, 2024 at 09:34:17AM +0800, Stephen Zhang wrote: > > > > > Dave Chinner 于2024年11月4日周一 20:15写道： > > > > > > On Mon, Nov 04, 2024 at 05:25:38PM +0800, Stephen Zhang wrote: > > > > > > > Dave Chinner 于2024年11月4日周一 11:32写道： > > > > > > > > On Mon, Nov 04, 2024 at 09:44:34AM +0800, zhangshida wrote: > > > Hi, I have tested the inode32 mount option. To my suprise, the inode32 > > > or the metadata preferred structure (will be referred to as inode32 for the > > > rest reply) doesn't implement the desired behavior as the AF rule[1] does: > > > Lower AFs/AGs will do anything they can for allocation before going > > > to HIGHER/RESERVED AFs/AGS. [1] > > > > This isn't important or relevant to the experiment I asked you to > > perform and report the results of. > > > > I asked you to observe and report the filesystem fill pattern in > > your environment when metadata preferred AGs are enabled. It isn't > > important whether inode32 exactly solves your problem, what I want > > to know is whether the underlying mechanism has sufficient control > > to provide a general solution that is always enabled. > > > > This is foundational engineering process: check your hypothesis work > > as you expect before building more stuff on top of them. i.e. > > perform experiments to confirm your ideas will work before doing > > anything else. > > > > If you answer a request for an experiment to be run with "theory > > tells me it won't work" then you haven't understood why you were > > asked to run an experiment in the first place. > > > > If I understand your reply correctly, then maybe my expression is the You didn't understand my reply correctly. I asked you to stop repeating the same explanation of your algorithm in response to every question I asked you. I asked you to stop trying to explain why something you just learnt about from a subject matter expert wouldn't fix your problem. I asked you to perform an experiment to confirm behaviour was as expected under your problematic workload. Your reply: > problem. What I replied before is: > 1. I have tested the inode32 option with the metadata preferred AGs > enabled(Yeah, I do check if the AG is set with > XFS_AGSTATE_PREFERS_METADATA). And with the alternating- > punching pattern, I observed that the preferred AG will still get fragmented > quickly, but the AF will not. > (That's what I meant in the first sentence of my previous reply...) is simply restating what you said in the previous email that I explicitly told you didn't answer the question I was asking you. Please listen to what I'm asking you to do. You don't need to explain anything to me, I just want you to run an experiment and report the results. This isn't a hard thing to do: the inode32 filesystem should fill to roughly 50% before it really starts to spill to the lower AGs. Record and paste the 'xfs_spaceman -c "freesp -a X"' histograms for each AG when the filesystem is a little over half full. That's it. I don't need you to explain anything to me, I simply want to know if the inode32 allocation policy does, in fact, work the way it is expected to under your problematic workload. -Dave. -- Dave Chinner david@fromorbit.com