Received-SPF: pass (google.com: domain of linux-kernel+bounces-45679-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1;
Message-ID: <2375481c-9d61-4f06-9f96-232f25b0e49b@intel.com>
Date: Wed, 31 Jan 2024 10:30:00 +0800
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v1 9/9] mm/memory: optimize unmap/zap with PTE-mapped THP
Content-Language: en-US
To: David Hildenbrand <david@redhat.com>, <linux-kernel@vger.kernel.org>
CC: <linux-mm@kvack.org>, Andrew Morton <akpm@linux-foundation.org>, "Matthew
 Wilcox" <willy@infradead.org>, Ryan Roberts <ryan.roberts@arm.com>, "Catalin
 Marinas" <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, "Aneesh
 Kumar K.V" <aneesh.kumar@linux.ibm.com>, Nick Piggin <npiggin@gmail.com>,
	Peter Zijlstra <peterz@infradead.org>, Michael Ellerman <mpe@ellerman.id.au>,
	Christophe Leroy <christophe.leroy@csgroup.eu>, "Naveen N. Rao"
	<naveen.n.rao@linux.ibm.com>, Heiko Carstens <hca@linux.ibm.com>, "Vasily
 Gorbik" <gor@linux.ibm.com>, Alexander Gordeev <agordeev@linux.ibm.com>,
	Christian Borntraeger <borntraeger@linux.ibm.com>, Sven Schnelle
	<svens@linux.ibm.com>, Arnd Bergmann <arnd@arndb.de>,
	<linux-arch@vger.kernel.org>, <linuxppc-dev@lists.ozlabs.org>,
	<linux-s390@vger.kernel.org>
References: <20240129143221.263763-1-david@redhat.com>
 <20240129143221.263763-10-david@redhat.com>
From: Yin Fengwei <fengwei.yin@intel.com>
In-Reply-To: <20240129143221.263763-10-david@redhat.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?S1lXb3MvMEJzaVJhUHB3Z3VDWitucHZGZHVPZ0VEeVBtM09TanB6RVR6M3N1?=
 =?utf-8?B?OStBUGE4My9MU1BpNEF0c3VxUVNIcC9yVjV0OFRVSXE2VU93d1M5eFIyMWFo?=
 =?utf-8?B?VDN0bEZwNzNIbm1Hc0xqZkdvRjRqZXNkNG9MU04rdlpJN3laeVM1V3pHVklk?=
 =?utf-8?B?OWxZZUgvTUFoTDZ1T1BlMWx4dk5wQkJpZThtQjh2Kzd5YXA0cHRJendBZmN1?=
 =?utf-8?B?S3E2WTFOOElnSW9tY0FlWVJuTnpjbktGeEVra1dMZjNFT3BXMjJCN0NGK3Nl?=
 =?utf-8?B?YVJoTTE5UVJYTFJUSnE5S0pWL3p2UWhUVlhXLzVjNnliYjNhb2FxbDNzU3FB?=
 =?utf-8?B?T010aXk5eHJramRNRmszTUY5bGFyRGpsY1B0ZmxuVm9sN3FvSGZpSzRNckhj?=
 =?utf-8?B?eCtEOWU2UVJCbEF6TWNWQS9GbUlDZnFrVUF1NlRhTi9hUTBFUDFKbm40VGcv?=
 =?utf-8?B?U0JYSEFOWjBwQmlBRHBBSjBXT0haa0daeWZDODV4SUxxUjg3YTdSbm9DQ1pi?=
 =?utf-8?B?OC9zbjV0VVhaWGZKcWI2OFpDZE4vTFl0WTY2YmdPRVZwTm5zek0rRHlLMDBY?=
 =?utf-8?B?b09UdzJkdWZ1Y2N6dXhSQlg3MHE3MVVVODcrWGIxSUZYS0NSMVQvTldxWE5k?=
 =?utf-8?B?RmljaWZtb0k1Wk5PRTJPb1E2QmtMOW0xYnJhcGNucVBDYXpwQ1pkTXFkTU0y?=
 =?utf-8?B?YlFUM1ZGZ0oyQVJCNW5NMy91WGhwRzA2Y1VqRko1NmVKRUZKZnpLNHo3YjJD?=
 =?utf-8?B?MlRkeXhKRWVFTzBRNFU0N1FqN0NGQThKSDFVcEtyVDY0TlpxcWZGNGl4NkRE?=
 =?utf-8?B?LzRlOStzR2N5NmFORjNrR3ZsQ09hb1BlTExrZ0YxT3VYNFRoSnU2YTMvQWRW?=
 =?utf-8?B?US9PTGRsTy81M3Rya3Y4TElUYkJyMzZCbUcyWTZzNEs5UmhZS2tpMStXazJy?=
 =?utf-8?B?M1FIbGRaU0lxZGk3Q0h4d3hWNkxibDhHV045V2VYMlJPeW4ySWE5Vi9rNnVp?=
 =?utf-8?B?YXVRcVpTNmhqR3F0dTlZdGRwOHNYMjdzd0lkRmI2RUU3RWFEbm9vZ3lRemZI?=
 =?utf-8?B?bUpjNlBMYk4rTzVnNjU4L3dqN1R3aW9pU3AxYmpXc05aKzdPWDZHa2pBSEVr?=
 =?utf-8?B?eVdnYmQwczU3b3FyL0hva1grWmcrZ2JmejBYWGZOczQ3bUM5QXZ2WVo5VHJ4?=
 =?utf-8?B?UVlaUEtIbHZUdmc5V2d0dWM3amJUU2tYR2RZODdtNFZ4eEJQSjJDVUNTcFRH?=
 =?utf-8?B?SWEyUDcxalhRQW0zUWxXcXI5MVZPZmVJR0Q2b2R0VVZYbGdTM3RFcEE2cE1G?=
 =?utf-8?B?QkRvU3lIQUhPOXhPQndWcUYrSHhIb2J5V1VVbHNWRVVSNGNTU0xFaVlCdVkz?=
 =?utf-8?B?M09KT1BqaEtRVzZDMDlBSHZPMjA4Q0dQL3NGaU0xUHNncitQd215QUpaTFR5?=
 =?utf-8?B?N3R1VVhMYTdHd1dEZUZMZ0NORDNNVzdEdlNqd0FBSVpSNm5LSTlid05BOGtn?=
 =?utf-8?B?eW5WVWhmU3RIcUViT3VzSzgwMTl3eXh2NjZkSXNNbWNadmRGM25xemtQOFJ6?=
 =?utf-8?B?OVg0QmU1RlVjMm82VXpVQkM1b2s5NTNzeVBaenhvZ2VQMVBRWnJTaGR0WDVx?=
 =?utf-8?B?aVg2NldMUFRCMzNjS3gxbm5mcW9MWEI0R2h2M3RLQ3J1VXovWVRCY1lMRUsr?=
 =?utf-8?B?ZkRGVWM5RTRUY0l6RFpBSFFJTHBBYUtQcm9aNEwwUmRBT1c3TTI3cTR4QTRo?=
 =?utf-8?B?ck1zdXBpbzhBZjR6OXpGQVM0QkpTcG1yT2g5VG0wMEVNcUVzVWpoUXBsWUp1?=
 =?utf-8?B?Q0ozbXVOWVg3a0lhVWhpS3lLM0ZaU3prdE0yUGcvWk9leE1IejdPYzd4OE9E?=
 =?utf-8?B?WGx5QW1iWXk0VWEyNHVLdFRJcnZxTGJCQVJka3o0cklCaGtySWh1MUtKUzRy?=
 =?utf-8?B?Y01TMFFNeVBha0xDWWRZTFNJZE1aWGV3SCt1K20rVUNOL201U3dVYktUcDdy?=
 =?utf-8?B?aDNGV1czZ3Y5NkVYNUVDdmRqdUgxZkpTUitvZWluSFByRzJWL3VqbHBMdVdF?=
 =?utf-8?B?d2ZyNTMyVmlUWUpMU2tLYmtaZEg5N0NSZllFbjJXYkhnOHhxQUNETmVvR1Ar?=
 =?utf-8?Q?PsHzN0h06jD6cARL2vGdD23qZ?=
X-MS-Exchange-CrossTenant-Network-Message-Id: 71c40ebe-37be-4ca8-4ed9-08dc22048c3a
X-MS-Exchange-CrossTenant-AuthSource: CO1PR11MB4820.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 31 Jan 2024 02:30:11.0358
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: B3GSZYqiBY55mgZ8olLl33EIjUrGFQWojdeCSO+i/VHYl1g8yBO48HmTkItngUYqWF4FHnUAz9FRI/SKFyUX2Q==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR11MB4917
X-OriginatorOrg: intel.com


On 1/29/24 22:32, David Hildenbrand wrote:
> +static inline pte_t get_and_clear_full_ptes(struct mm_struct *mm,
> +		unsigned long addr, pte_t *ptep, unsigned int nr, int full)
> +{
> +	pte_t pte, tmp_pte;
> +
> +	pte = ptep_get_and_clear_full(mm, addr, ptep, full);
> +	while (--nr) {
> +		ptep++;
> +		addr += PAGE_SIZE;
> +		tmp_pte = ptep_get_and_clear_full(mm, addr, ptep, full);
> +		if (pte_dirty(tmp_pte))
> +			pte = pte_mkdirty(pte);
> +		if (pte_young(tmp_pte))
> +			pte = pte_mkyoung(pte);
I am wondering whether it's worthy to move the pte_mkdirty() and pte_mkyoung()
out of the loop and just do it one time if needed. The worst case is that they
are called nr - 1 time. Or it's just too micro?


Regards
Yin, Fengwei

> +	}
> +	return pte;
> +}