Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:4 as permitted sender) client-ip=2620:137:e000::3:4;
Message-ID: <9a65e703-3476-4584-bec0-8f41198d840f@intel.com>
Date:   Tue, 28 Nov 2023 17:50:57 +0100
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH net-next v5 03/14] page_pool: avoid calling no-op
 externals when possible
Content-Language: en-US
To:     Jakub Kicinski <kuba@kernel.org>
CC:     Yunsheng Lin <linyunsheng@huawei.com>,
        Christoph Hellwig <hch@lst.de>,
        Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
        Michal Kubiak <michal.kubiak@intel.com>,
        Larysa Zaremba <larysa.zaremba@intel.com>,
        Alexander Duyck <alexanderduyck@fb.com>,
        David Christensen <drc@linux.vnet.ibm.com>,
        Jesper Dangaard Brouer <hawk@kernel.org>,
        "Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
        Paul Menzel <pmenzel@molgen.mpg.de>, <netdev@vger.kernel.org>,
        <intel-wired-lan@lists.osuosl.org>, <linux-kernel@vger.kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        "Paolo Abeni" <pabeni@redhat.com>
References: <20231124154732.1623518-1-aleksander.lobakin@intel.com>
 <20231124154732.1623518-4-aleksander.lobakin@intel.com>
 <6bd14aa9-fa65-e4f6-579c-3a1064b2a382@huawei.com>
 <a1a0c27f-f367-40e7-9dc2-9421b4b6379a@intel.com>
 <20231127101720.282862f6@kernel.org>
From:   Alexander Lobakin <aleksander.lobakin@intel.com>
In-Reply-To: <20231127101720.282862f6@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?MUxDWFJkYlBaUEdNZThyT1FGYzNUNXZTbWhYMm9EUVVjYTRTVzYyelhaUkg4?=
 =?utf-8?B?K1o1ZEdnNFhCVTY4MmJOR3pKNURONnlNbFJCWmd4QlVLOHF5azRJazl2RnY1?=
 =?utf-8?B?OElsbW44Y1JVSnhCQzArZEcxT0toSDhQMjl5VUUreVVMcHZaZ2U1VnhYcUxj?=
 =?utf-8?B?dlJkYkx0SUpDc1gyVUc1MnFON1JDVkMrMUFYbEZ6VENEM01uTitITWRyNGJh?=
 =?utf-8?B?Njl6YzhQMENlMVZmRGVYckJKRjdSUXFJVG1Cd2RSaXF1bld6MFFOOHNNYkla?=
 =?utf-8?B?UVpYMFNhaVgramhseStIZzNOVmc1RUwwai9VL1U2UWlUc0VpOGhqRkRDUEda?=
 =?utf-8?B?bXVuSDZuTDBYRS9LRHowLzg2d01qNFFxVGJ4OVQxWnErWnZlMnMzYm5USUp3?=
 =?utf-8?B?YnczblBoYlhNSE1rKzlodXUvQWtmbk4rZmx6NkhLZHpZV1BYeE1WNTBxaHYz?=
 =?utf-8?B?WFh4UWZQTVB1cjFIU09CYXp0TWJURGxKWlFud0tqYUZnckZFY0FOaitRaUxH?=
 =?utf-8?B?enhPNlYrQ1h3M0VMZ3QyOFZXTjgwMXV2Rlc5RE1kWnlwb0dFa1VyeWFVVjFo?=
 =?utf-8?B?NmlGandUWERWdTJ1WVBQaEFDWGdDYkJJNXE5WWFSQkExUlI4d1d1L2NLOGRG?=
 =?utf-8?B?T09EYjNrSnRHVXErMU04NEZNWWt6M0hteDlwNDdKcGt0VWhTRmdTVVZpN1NI?=
 =?utf-8?B?dkI3Qk4wTzhmV0tZOFZSdVBPdFN6VmpkWVEyOWZnc0tQTGFsZWU0R3pQbVMz?=
 =?utf-8?B?NEI5SjkvZGZOaVlnWmpUTHY1eTdzQW56Q2RQR1dWaFc1d2YxSHVxd3pUUlI1?=
 =?utf-8?B?MU5Cb05RWVJ1RTcvUHZrNURPdkJjMFhuSTFIM2pidGJ0cUVSS2dOdmozK242?=
 =?utf-8?B?SmxhOTJjNDZ4cGsySGJCSVZYNkg3aDVVRlVxbk83a3c2NkRQcW4yNXN0c1p2?=
 =?utf-8?B?QTBrWXoyalYyUUZTY3dPYTZ4VnBIWmgrQUc3dGRSTjVXRzNnVnNMMmVtc2Qv?=
 =?utf-8?B?Vm1wZjJmMDR1YkVRSm9vS2tIS1hUKzJYZXZjejdYOFFxMWUvM3h4OFlVOXF4?=
 =?utf-8?B?amhNQUtrd0pVcXBtSTR2UHQyL3NsVFM2MUJSOVJiL1BkajFMeXhPTnlCRy92?=
 =?utf-8?B?Y2VrbzVKakZ3RzdBQ3U4WDBjNVlnVXd0cGcxNXBLTkk4N2ZaZURPa0NuMmpt?=
 =?utf-8?B?ZmFtQ2hhZ2RKY3VNZnBWYjN5ZFFpN1ZqQlI1S0VFNEdQWDVJVktYU3krbWpE?=
 =?utf-8?B?a1VJSk0rYjZ4NmZOdHhZbGVSMEh2dy9WTkIvc3M1V2ViK2tNdk9MWGxyYkVS?=
 =?utf-8?B?bWlFOEYrRzR0dGxXbEZKcGw3WG5xTS9sZEJHK2dOWGpzME40SnAvZnZkM1la?=
 =?utf-8?B?SDVjeDhLR0w1RldCZnNpeVVPWWlTbkVmM3l0UHc2eC9WbWliby9XZmdjb2R1?=
 =?utf-8?B?RUJVVHNOQ0ttRHBSWHBrblRTSGZZTlVWL1l4ampMWE1XSVc4L2J3OW1WSmVx?=
 =?utf-8?B?Z2d0NUwwZCt0Y2ZkN0wyWFBIUzJkUXowVHhMd2dTSUEzVlJYSGpoTHV0L2dn?=
 =?utf-8?B?T3NzRS8wZHU0azNFQVo3SVNLVFY0eEhJRmhEUStWSWtTR1JGQU0za2M0Tk5o?=
 =?utf-8?B?SWd4VUVIZ1NhZFVRK28vaTR6TGJPTnhYTmx0MHFBckZzTStzeU9IUTNTQ2tv?=
 =?utf-8?B?WGQzUTEzZy9XTWU2Qi9MTCt6OFp3dEpZZ3VRRW9HdlpHVEJWbFZ3TENWRGhX?=
 =?utf-8?B?M0NyWEZYOWIzUDQ5WjJxMnZ6NENIV29rOGU3YzBZSWMzaUt0NEwxSzJnbDla?=
 =?utf-8?B?Z1ZGMy92L1MzdjhqSjlKYXQ0Um9GR0hpWG5rQ2Qxb2M0SWlHTU5jNjNJTDd5?=
 =?utf-8?B?ZmlaeG1SaG8wbCtWdzcwcTFrOXNoZlVrZDdIWmR0MER0N1VBcWRaLzh5U053?=
 =?utf-8?B?aS9BVkVPSnhrUTRCV1RxTlBUQTBsamx4cFZSMDNBUHpMS2s2VW4zNWVhalpx?=
 =?utf-8?B?b1p1bUNnWUZkUGhnKzZuWWRLOENlWXh6M2orbGlHOUVqOG4rbnhDdFBqaTRD?=
 =?utf-8?B?QUpFRkY3cFVLUFpXbDhPZE1tSElyckp1UkVCMGRqZ1hJYjhuakU2cHFQT1d3?=
 =?utf-8?B?dFpOTituNjlnWHQwTU5EZFdTMmx1N25nTnRuNTRHMUxXU1N4c0JWS0ptUXBP?=
 =?utf-8?B?NlE9PQ==?=
X-MS-Exchange-CrossTenant-Network-Message-Id: b7c4cecd-b54d-4c93-932e-08dbf032471f
X-MS-Exchange-CrossTenant-AuthSource: DM6PR11MB3625.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Nov 2023 16:51:33.7749
 (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: XnpQJZ0eyorwBPfo1ll6kMGT/nGzTA99sNY0zFxKyN8Se0zMjY/Et96Y2zULT3+ThLubZARWUp9gBYxkAnUhYL+96O0M5edbTi5eqLTKd/k=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA2PR11MB5019
X-OriginatorOrg: intel.com
X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED,
	DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE
	autolearn=unavailable autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on howler.vger.email
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (howler.vger.email [0.0.0.0]); Tue, 28 Nov 2023 08:51:54 -0800 (PST)

From: Jakub Kicinski <kuba@kernel.org>
Date: Mon, 27 Nov 2023 10:17:20 -0800

> On Mon, 27 Nov 2023 15:32:19 +0100 Alexander Lobakin wrote:
>>> Sorry for not remembering the suggestion:(  
>>
>> In the previous versions of this change I used a global flag per whole
>> page_pool, just like XSk does for the whole XSk buff pool, then you
>> proposed to use the lowest bit of ::dma_addr and store it per page, so
>> that it would be more granular/precise. I tested it and it doesn't
>> perform worse than global, but in some cases may be beneficial.
> 
> FWIW I'd vote to stick to per-page pool. You seem to handle the
> sizeof(dma_addr_t) > sizeof(long) case correctly but the code is
> growing in complexity, providing no known/measurable benefit.
> We can always do this later but for now it seems like a premature
> optimization to me.

Yeah, this also seems more logical and optimal to me. Will wait a bit
for a possible reply from Chris and then send the next rev.

Thanks,
Olek