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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qTDMu-00F6HF-D9; Tue, 08 Aug 2023 03:26:48 +0000 Date: Tue, 8 Aug 2023 04:26:48 +0100 From: Matthew Wilcox To: Miaohe Lin Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: remove unneeded __meminit annotation Message-ID: References: <20230808015831.608454-1-linmiaohe@huawei.com> <308f326d-c7ae-be49-22af-189a81a89aa2@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 06DD3A0005 X-Stat-Signature: 46bmniehzsb17ykg6j6ihrrbhix1y8jx X-Rspam-User: X-HE-Tag: 1691465210-552729 X-HE-Meta: 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 s6g8hqhP sC2HdIWjsQ2xecEy/Inh5lSUNn3ZWc1Z58GV5sQ3vKAdMRmkusJCW2GrMkqaqNwC3oWbQFEB2lI3tgOIKf3XC8HclmzFJqSHFDsEWzVOANKe2YCa4dyHgC43RqJYWlRBD2nXIckeFnaeMGGCyP2r+7DXQnCy3ptteOfYvfHMCoPNARIcuOgZU+3iZQQ== 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: On Tue, Aug 08, 2023 at 04:16:57AM +0100, Matthew Wilcox wrote: > On Tue, Aug 08, 2023 at 11:08:36AM +0800, Miaohe Lin wrote: > > On 2023/8/8 10:31, Matthew Wilcox wrote: > > > On Tue, Aug 08, 2023 at 09:58:31AM +0800, Miaohe Lin wrote: > > >> kswapd_stop() and kcompactd_stop() are only called when MEMORY_HOTREMOVE > > >> is enabled. So wrap them under CONFIG_MEMORY_HOTREMOVE and further remove > > >> __meminit annotation. No functional change intended. > > > > > > I don't understand why this is an improvement. If CONFIG_MEMORY_HOTREMOVE > > > is disabled, the linker drops this section (... right?) If it's enabled, > > > > When CONFIG_MEMORY_HOTREMOVE is disabled, without this patch: > > > > size mm/compaction.o > > text data bss dec hex filename > > 103164 30873 0 134037 20b95 mm/compaction.o > > > > size mm/vmscan.o > > text data bss dec hex filename > > 158775 49612 64 208451 32e43 mm/vmscan.o > > > > while with this patch: > > > > size mm/compaction.o > > text data bss dec hex filename > > 102915 30865 0 133780 20a94 mm/compaction.o > > > > size mm/vmscan.o > > text data bss dec hex filename > > 158534 49604 64 208202 32d4a mm/vmscan.o > > > > We can reduce each .o by ~250 bytes. > > But this is before the linker step! That will be where the meminit > sections get dropped. Assuming they are; I haven't verified. You need > to compare before/after of the vmlinux, not the individual .o files. Ah, found it: #if defined(CONFIG_MEMORY_HOTPLUG) #define MEM_KEEP(sec) *(.mem##sec) #define MEM_DISCARD(sec) #else #define MEM_KEEP(sec) #define MEM_DISCARD(sec) *(.mem##sec) #endif in include/asm-generic/vmlinux.lds.h So yeah, I think this patch is garbage.