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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772120745; bh=xrU8eCDmAt74z4SHgfuBriV+ZahnT3PtEGbapliyWH8=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Clbv3rTxl5B7aDaexrscHTgYx/U/l4RM2L0DhFFS97w8Fg52ZNruvxRJc6o/okHlY k9ZIq2ApyP8nmPRxaRR+SI7bTpU9EFPOQTZ8AIIM+ft+3i+G8qkVZ0f0fsqY1NAzSP H2uOkV9c7yq5atNbOrDak0D8HXltMo8K5IKtMry6QNwYNe64v9hAzy28lu12xs2zRV /7LiOa6TnNAL3/PxPEhQodpn3O7zHxMcd3ax/5y4Zw9Y43OwAhtuAS898jyQkwJY1e nA1aEbBUK5GQJiPko6rC7JaZ17fuIrFMp6/kP/UxYzrFeoLne3Qkc7R3BVnxrHCAh3 Q0rSUTLxnOTfA== Message-ID: <8a5277e0-d70e-4849-9763-ed90e350a118@kernel.org> Date: Thu, 26 Feb 2026 16:45:40 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH mm-new v8 2/4] mm: khugepaged: refine scan progress number To: Vernon Yang , akpm@linux-foundation.org Cc: Wei Yang , lorenzo.stoakes@oracle.com, ziy@nvidia.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vernon Yang References: <20260221093918.1456187-1-vernon2gm@gmail.com> <20260221093918.1456187-3-vernon2gm@gmail.com> <20260224035247.r6mxsfcpiev4wnce@master> <1da56bbb-9211-42d7-9b08-3ee56d2b538d@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: zq13ah8cm8guoijy15rgsxmu1dt6m7ny X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 6984D140009 X-HE-Tag: 1772120746-741225 X-HE-Meta: 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 IOS8bcd9 mRD+QABcNV6Cbo7jgtWOLWm5skfvlAyid3pZFzd6XWKANBF4gHkQB/iHdk4PUPOYuw2BL++nEXPfHV3FoZMoVgELXdznZ82MPllvM5tPFUrtU+26ZIhjnBAB8hdJgK/qytZJeFMEBFRHURSnwvbLxDeRB+oYXtkBDgM3vJ/uxeqww+lWamRGjszBPoeJLfnTPzzVNC6oaWLsTB+xT0Q9CjYIkt4Eyb9710zU+LUsDQTktbkFWdIzcnWQfZztvT0rSfP3unP1AoWVat/HW9blAgKXoxB0vsRePJN/ToJb2Q+LDUDrt2tXaFAwVkx5MLIY6BBe7m6zmrSEpf2I= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2/26/26 15:31, Vernon Yang wrote: > On Wed, Feb 25, 2026 at 03:29:05PM +0100, David Hildenbrand (Arm) wrote: >> On 2/25/26 15:25, Vernon Yang wrote: >>> >>> Thank you for suggestion. >>> >>> Placing it inside "struct collapse_control" makes the overall code >>> simpler, there also coincidentally has a 4-bytes hole, as shown below: >>> >>> struct collapse_control { >>> bool is_khugepaged; /* 0 1 */ >>> >>> /* XXX 3 bytes hole, try to pack */ >>> >>> u32 node_load[64]; /* 4 256 */ >>> >>> /* XXX 4 bytes hole, try to pack */ >>> >>> /* --- cacheline 4 boundary (256 bytes) was 8 bytes ago --- */ >>> nodemask_t alloc_nmask; /* 264 8 */ >>> >>> /* size: 272, cachelines: 5, members: 3 */ >>> /* sum members: 265, holes: 2, sum holes: 7 */ >>> /* last cacheline: 16 bytes */ >>> }; >>> >>> But regardless of khugepaged or madvise(MADV_COLLAPSE), "cur_progress" >>> will be counted, while madvise(MADV_COLLAPSE) actually does not need to >>> be counted. >>> >>> David, do we want to place "cur_progress" inside the "struct collapse_control"? >> >> Might end up looking nicer code-wise. But the reset semantics (within a >> pmd) are a bit weird. >> >>> If Yes, it would be better to rename "cur_progress" to "pmd_progress", >>> as show below: >>> >> >> "pmd_progress" is misleading. "progress_in_pmd" might be clearer. >> >> Play with it to see if it looks better :) > > Hi Andrew, David, > > Based on previous discussions [1], v2 as follow, and testing shows the > same performance benefits. Just make code cleaner, no function changes. > > If David has no further revisions, Andrew, could you please squash the > following clean into this patch? If you prefer a new version, please let > me know. Thanks. Do we also have to update the resulting patch description? Patch itself LGTM. -- Cheers, David