Received-SPF: pass (google.com: domain of linux-kernel+bounces-148083-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Message-ID: <935fea29-86ef-4cfb-a370-0b9616a0c279@prevas.dk>
Date: Wed, 17 Apr 2024 09:53:43 +0200
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH] seq_file: Optimize seq_puts()
To: Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
 Alexander Viro <viro@zeniv.linux.org.uk>,
 Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>
Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org,
 linux-fsdevel@vger.kernel.org
References: <5c4f7ad7b88f5026940efa9c8be36a58755ec1b3.1704374916.git.christophe.jaillet@wanadoo.fr>
 <4b1a4cc5-e057-4944-be69-d25f28645256@wanadoo.fr>
Content-Language: en-US, da
From: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
In-Reply-To: <4b1a4cc5-e057-4944-be69-d25f28645256@wanadoo.fr>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0:
	=?utf-8?B?QXVLSFlKMlo4by9TSmd6eWJBYVdQd01pdTY2eFltNTNiQWYzT2orSHdnMjll?=
 =?utf-8?B?Z1NNaElzMVNOeCtTTmVxc1pZWVFPd001bWRha3J0ZWVmSFZ5bXQ3RHZqc1l5?=
 =?utf-8?B?YWswTFFURk1xTzl2YmNHNXRNOHV3cXNhZGJBNFJOZUl3SXAwaElua0ZRM1Az?=
 =?utf-8?B?aktMZitqRTJUWE0xUGVUVWxZTzdjU0R6YzFMVWQ0WWdJaDdRRTQybUQyZk4y?=
 =?utf-8?B?MXRwMXhOWkVWV2hPb3UxRDQwN1ZNdVRlUDBxNlV1QmF6dm1JSDZIZFhpMmNm?=
 =?utf-8?B?VGNoSXVWd1NkckVod2pvRTNMbzlLR2VtMWZ0dmJ4WmtPQURqY2NFTmRGbE4r?=
 =?utf-8?B?ekJIMGY4K0hXWjdjdzhIY3YrYXNXMUZoTnFpM2Q4RWFaY0hDM3hzeEJ1dDE2?=
 =?utf-8?B?NUVYeGllNlo1KzRuOTZQb09LRUpHTTRsdjkxMm0rZXk3QTR3UW1wcU1KRlpq?=
 =?utf-8?B?d3J4U3FuTXpzUlVwRTNNMTFrekFaVVFzUG5LdWJuTnl3Y3V3Q2lSWDU4N2R2?=
 =?utf-8?B?azgwLzdyM0dZc0dsOEpQZGY0SkFNQVAvc1pRT25wTTBjVVBIVVRYVCtLRnB4?=
 =?utf-8?B?TVZpTzd5dzZTTjNOalhiK0NIZnVGdTNOd0NNYVRqSk1kcXhPZ1ZwLzJYWlQw?=
 =?utf-8?B?OFVhOFRuRXlyems0aStxTGhSdVoxbzl5OUF5M3JZWktsOVhQK1pZL3dTZ2w5?=
 =?utf-8?B?ZUphbXZCZmo0Y05VTFpTaGNrNmZJdUhPRVFBWkkxRXNXd0pyK0p6bCs4UC9I?=
 =?utf-8?B?ditmby9pWlNTWCtxV3c2MWluVmhYUFVHYTJkUzRnbld5WHRKbmxYWjFZVVNW?=
 =?utf-8?B?NXdwaFlXazVpODdWU0VSWGtGbGtvSXJZdDdud2ZHS0szOW5hQnQ4bHFkR0JI?=
 =?utf-8?B?RmNIQS9NYkt4MnQ3NkRmZ2krS3VuSUJjWUR1NTVzTE5DdS9BVlBvQlZwVUFI?=
 =?utf-8?B?SWhLeWRFSnkrYnZGckgvNFhGNTd1N3lRTXArRE0rQnVjd21BUG9QeW8zWkZQ?=
 =?utf-8?B?clpwMVdRcjhnMEd6eVZpQnI5Q1k4c3pzaHh4enhJVXlubVNlM014aGMxZ2pr?=
 =?utf-8?B?aEFWb21MWFIxNmJMUUN4Z1IyL1c1cEZkU1owY0NkME5TNzhYVnJjeWdlNndP?=
 =?utf-8?B?ZUhYSjBhN0Z6UUFKUERoeEJEYzRJNTJLRi9tTG52blJFckdiTFhPc1lHeXU5?=
 =?utf-8?B?Y0ZiM1IwWEM0V2NJcVNJVXhjTlc0RXFNU25kS2QrZHlWaWFVcXBZc2tyWWph?=
 =?utf-8?B?K0o2ay9LaWZONDdacm4xM0RJM1ZmdjZwdkE4Q0I1dlBjcVUzOUFTYzEvTnVq?=
 =?utf-8?B?QTYydStVWTdKZUtjdUNBQnBpQVM0Qm9GcVNjMnZRUzdQU0U0RlJjdWgzQ1FU?=
 =?utf-8?B?NXE4aVJoVk5TbW1kWnYwMHc5RG5KNEV5dVFibk5iSGl3TENJZDd1eUpsNk8x?=
 =?utf-8?B?VDMxa3d2eWpQaE50TFRtbUVwWmhORDlBeXVkM3F1TUcwSktKU2p3Tnh3cC9o?=
 =?utf-8?B?SE8za1YybVVaYkk0R1ZUcmZoTGFpNG5HanpKdStZK1ltWU5Rcm56dUc5T2t2?=
 =?utf-8?B?enNndVBKazQwcVI4TTVKWUFkS09vVUJGeTZHMVpFdE5IUXFOYU9hbE1vWW9J?=
 =?utf-8?B?Ui96NVBNdG1ybkE0OGhFQ0JROW9QT0lyOEJGQXRCTG5JUnkrV0RTaG1WZGZm?=
 =?utf-8?B?OVhYVXZMVU9GclY2R1JTSGxqSk4vd3d1dzR1M3ZXQTdsT3lCWkVxVlNXNU5Z?=
 =?utf-8?B?QW9YbVNqcVowMWZBd3I3TE5KZTA0YWJMb0NGbkQra0JtbnUrSDhFNi9yYVQy?=
 =?utf-8?B?TEFXejdRQjBaMEpLcC9KcHNCeXl4VTl4QStUOUYzdU16TnZEZ2RvNkhJeUZT?=
 =?utf-8?B?bkFLNTY2ZWJicC9DWEN4OW9LQU5TMFY2ajlMNHgvdFhEWVY3b1o5UDd1U0kw?=
 =?utf-8?B?TmNneFMwNFY0anV0VXB1ZCsrcjZXYk50VHhrL2JXQTVuRVhYR2k2TVZjSjN3?=
 =?utf-8?B?QVBnTzl1VkhBUktJbU1nRTZnM2YvdUVuWVZnSmZZNEhTQU1nN0NML1ZYSDFq?=
 =?utf-8?B?Rk1iUDF5R2lwSmRTdHJuYlNqRGRReHZGVGQ2MG05UStLL3dITVUvNE9zRU85?=
 =?utf-8?B?N2lwYzJJOUlVZC9PdnIvTDlQR2V1TDRNajFraGJoL29UWElLYTMxeXpqV0Nw?=
 =?utf-8?B?eHc9PQ==?=
X-OriginatorOrg: prevas.dk
X-MS-Exchange-CrossTenant-Network-Message-Id: 91676fee-9447-45e9-faf6-08dc5eb38259
X-MS-Exchange-CrossTenant-AuthSource: DB9PR10MB7100.EURPRD10.PROD.OUTLOOK.COM
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 Apr 2024 07:53:46.1372
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: d350cf71-778d-4780-88f5-071a4cb1ed61
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: xxv7aKE7EjMO4jp1j1+cRwSc7olUw/uDUn8x569TzaPqSjSKT9Y/KOdupn1G2xR5nmyeBK+bqxMCrovO4haiDkuPhHxNqsljmZxYuRwnMk0=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI0PR10MB8693

On 15/04/2024 22.47, Christophe JAILLET wrote:
> Le 04/01/2024 à 14:29, Christophe JAILLET a écrit :
>> Most of seq_puts() usages are done with a string literal. In such cases,
>> the length of the string car be computed at compile time in order to save
>> a strlen() call at run-time. seq_write() can then be used instead.
>>
>> This saves a few cycles.
>>
>> To have an estimation of how often this optimization triggers:
>>     $ git grep seq_puts.*\" | wc -l
>>     3391
>>
>> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> 
> Hi,
> 
> any feed-back on this small optimisation of seq_puts()?

While you're at it, could you change the implementation of the
out-of-line seq_puts (or __seq_puts if it gets renamed to that) to
simply be seq_write(seq, s, strlen(s)) instead of duplicating the
overflow/memcpy logic.

Rasmus