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[141.239.158.86]) by smtp.gmail.com with ESMTPSA id ns21-20020a17090b251500b002a068485de6sm2704002pjb.3.2024.03.25.13.26.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Mar 2024 13:26:21 -0700 (PDT) Date: Mon, 25 Mar 2024 10:26:20 -1000 From: Tejun Heo To: Kemeng Shi Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, willy@infradead.org, bfoster@redhat.com, jack@suse.cz, dsterba@suse.com, mjguzik@gmail.com, dhowells@redhat.com, peterz@infradead.org Subject: Re: [PATCH 6/6] writeback: remove unneeded GDTC_INIT_NO_WB Message-ID: References: <20240320110222.6564-1-shikemeng@huaweicloud.com> <20240320110222.6564-7-shikemeng@huaweicloud.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 3ABBA1A000C X-Stat-Signature: uiepgsbtym7fnbu3ctirstoxb5zkkgft X-HE-Tag: 1711398382-763646 X-HE-Meta: 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 AV9vR2E1 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Mar 21, 2024 at 03:12:21PM +0800, Kemeng Shi wrote: > > > on 3/20/2024 11:15 PM, Tejun Heo wrote: > > Hello, > > > > On Wed, Mar 20, 2024 at 07:02:22PM +0800, Kemeng Shi wrote: > >> We never use gdtc->dom set with GDTC_INIT_NO_WB, just remove unneeded > >> GDTC_INIT_NO_WB > >> > >> Signed-off-by: Kemeng Shi > > ... > >> void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty) > >> { > >> - struct dirty_throttle_control gdtc = { GDTC_INIT_NO_WB }; > >> + struct dirty_throttle_control gdtc = { }; > > > > Even if it's currently not referenced, wouldn't it still be better to always > > guarantee that a dtc's dom is always initialized? I'm not sure what we get > > by removing this. > As we explicitly use GDTC_INIT_NO_WB to set global_wb_domain before > calculating dirty limit with domain_dirty_limits, I intuitively think the dirty > limit calculation in domain_dirty_limits is related to global_wb_domain when > CONFIG_WRITEBACK_CGROUP is enabled while the truth is not. So this is a little > confusing to me. > Would it be acceptable to you that we keep useing GDTC_INIT_NO_WB but > define GDTC_INIT_NO_WB to null fow now and redefine GDTC_INIT_NO_WB when some > member of gdtc is really needed. > Of couse I'm not insistent on this. Would like to hear you suggestion. Thanks! Ah, I see. In that case, the proposed change of removing GDTC_INIT_NO_WB looks good to me. Thanks. -- tejun