From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.zx2c4.com (lists.zx2c4.com [165.227.139.114]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B7D9DCA0EED for ; Fri, 22 Aug 2025 14:00:15 +0000 (UTC) Received: by lists.zx2c4.com (ZX2C4 Mail Server) with ESMTP id 3435bce1; Fri, 22 Aug 2025 14:00:13 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lists.zx2c4.com (ZX2C4 Mail Server) with ESMTPS id 1058e727 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO) for ; Fri, 22 Aug 2025 14:00:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1755871208; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=K6aDoQ2nZkjhSfUgeR22UAGAXQBWHHuCN2RUasZyd3Q=; b=UcXxTvqdvhg3bu2m9ZujNAUrGvfVyxQEIj8ESUTpDmlq4iw0JPD+2rhqvZvpIou2/YfzTp KtAMTjL9d8FA0BjPOAvZUg6aThkPC6nXXSii8xByg9qwjboljceEXVdTbVRqZeToisyN1z bNkaAcm52LGXjFoViTZwZqgutcPsNC8= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-222-bfv2oxl4NnGgmZbuT4HYqg-1; Fri, 22 Aug 2025 10:00:07 -0400 X-MC-Unique: bfv2oxl4NnGgmZbuT4HYqg-1 X-Mimecast-MFC-AGG-ID: bfv2oxl4NnGgmZbuT4HYqg_1755871201 Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-45a256a20fcso12451515e9.2 for ; Fri, 22 Aug 2025 07:00:06 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1755871201; x=1756476001; h=content-transfer-encoding:in-reply-to:autocrypt:content-language :from:references:cc:to:subject:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=K6aDoQ2nZkjhSfUgeR22UAGAXQBWHHuCN2RUasZyd3Q=; b=M/30+ay94aeQnggj2Wp0AsAVi3WJrWxbmGdugGPUQmypBP6Dop/PJxt15cfcAcHKK7 WgtVq8QsmqyAAPwkvrMwxuyfXiKsHOXEYxFM2CDfSsalUYGk1XPUexcBjv2SwT//m409 qJkHqs6MkqXfWm3aqUw2LmA99NUGCk4PUhDVZGdgFp17I30esm4LwsIsLdrBgn211xv/ GkyTtaH4SRf3u0EJxAKy932zGY7HCrNtZrtfnpRObL0+MeLJAL3oqdG7XvB2ernSihD/ YUI9wGZOc8mUwDXOxTgp7LMUSW0S2gyyJkInYLCKY1MNLqCU8ihbAxDzcjKMw8bMkAzs sQOw== X-Forwarded-Encrypted: i=1; AJvYcCVVnqQ6sceeDLQzsK9FQ/SbI79vNRRNNhQ8rq1Hvye+5+AjJe5EdDHeaDuHhiFmApnFb3lhaHbKP4g=@lists.zx2c4.com X-Gm-Message-State: AOJu0YwChscxf9SpZEUQo/Tq3QbprvtL21iNBL0Cenk4dGPqWxqKC1QH ITcobW0y+nKPWIep50Z5vnQ+PCNH+svIhasn1okP/PbF/nCVAkwgHq3MEOzc/ci088h9rS21QUr Sok0x1qUkbBX/elKd7EL7ktnkvFQmitlna1XmftD3yKzgzYXsQ5sZije+oVR7Pw== X-Gm-Gg: ASbGncu8/PzDCuV//oedYHsqBFKczbUkEuqd45EawmxYs+9m9/KdMXQGu9u4vvyZui3 pFooTni3A9EoxWobV3Kll4owVtCoTQ4uqLxj1c2d8IR9x9qbnaMyO7wfdrNG8vz9FklWSVaigrF 6MVWyeSBVgVq5/nFuzv6/HSKrVxW1x+Ge9kIqSEaoLX8m/JgXTm34YeXlpyhYs3+9Gx3ZCRm8Y8 3w5ApWI/L424VQ18qyHG7gd/d4zapiYjuV3Iw+sWGNV0asgGbPGR4y3P+rMlM7lhauu0dE43pdx JiJmvzgxpydwJrPBwdxQBBIaJpLfwd3JQfFh4KZnjQOKw+dyio3YWemiFDy9vpXOPJwzm6ZUBsK B1UkdnPjp8KkD5k0p7w7mRgpnqtBpF5VMNEKd5JNAIyk5S31opYCEn4jdjREUNFkKLHo= X-Received: by 2002:a05:600c:1554:b0:459:e06b:afb4 with SMTP id 5b1f17b1804b1-45b5179b4fcmr28181815e9.4.1755871200673; Fri, 22 Aug 2025 07:00:00 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGwWP+gcyHz5PASikvY9eCVK8ixT+7ngDF6OHjbY0O7J0DLjuT/QVU1ki3KQXQcrTer6FnpTg== X-Received: by 2002:a05:600c:1554:b0:459:e06b:afb4 with SMTP id 5b1f17b1804b1-45b5179b4fcmr28181195e9.4.1755871200176; Fri, 22 Aug 2025 07:00:00 -0700 (PDT) Received: from ?IPV6:2003:d8:2f2e:6100:d9da:ae87:764c:a77e? (p200300d82f2e6100d9daae87764ca77e.dip0.t-ipconnect.de. [2003:d8:2f2e:6100:d9da:ae87:764c:a77e]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45b57498d9csm82525e9.22.2025.08.22.06.59.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 Aug 2025 06:59:59 -0700 (PDT) Message-ID: <473f3576-ddf3-4388-aeec-d486f639950a@redhat.com> Date: Fri, 22 Aug 2025 15:59:57 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 18/35] io_uring/zcrx: remove "struct io_copy_cache" and one nth_page() usage To: Pavel Begunkov , linux-kernel@vger.kernel.org Cc: Jens Axboe , Alexander Potapenko , Andrew Morton , Brendan Jackman , Christoph Lameter , Dennis Zhou , Dmitry Vyukov , dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, iommu@lists.linux.dev, io-uring@vger.kernel.org, Jason Gunthorpe , Johannes Weiner , John Hubbard , kasan-dev@googlegroups.com, kvm@vger.kernel.org, "Liam R. Howlett" , Linus Torvalds , linux-arm-kernel@axis.com, linux-arm-kernel@lists.infradead.org, linux-crypto@vger.kernel.org, linux-ide@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mips@vger.kernel.org, linux-mmc@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, Lorenzo Stoakes , Marco Elver , Marek Szyprowski , Michal Hocko , Mike Rapoport , Muchun Song , netdev@vger.kernel.org, Oscar Salvador , Peter Xu , Robin Murphy , Suren Baghdasaryan , Tejun Heo , virtualization@lists.linux.dev, Vlastimil Babka , wireguard@lists.zx2c4.com, x86@kernel.org, Zi Yan References: <20250821200701.1329277-1-david@redhat.com> <20250821200701.1329277-19-david@redhat.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZoEEwEIAEQCGwMCF4ACGQEFCwkIBwICIgIG FQoJCAsCBBYCAwECHgcWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaJzangUJJlgIpAAKCRBN 3hD3AP+DWhAxD/9wcL0A+2rtaAmutaKTfxhTP0b4AAp1r/eLxjrbfbCCmh4pqzBhmSX/4z11 opn2KqcOsueRF1t2ENLOWzQu3Roiny2HOU7DajqB4dm1BVMaXQya5ae2ghzlJN9SIoopTWlR 0Af3hPj5E2PYvQhlcqeoehKlBo9rROJv/rjmr2x0yOM8qeTroH/ZzNlCtJ56AsE6Tvl+r7cW 3x7/Jq5WvWeudKrhFh7/yQ7eRvHCjd9bBrZTlgAfiHmX9AnCCPRPpNGNedV9Yty2Jnxhfmbv Pw37LA/jef8zlCDyUh2KCU1xVEOWqg15o1RtTyGV1nXV2O/mfuQJud5vIgzBvHhypc3p6VZJ lEf8YmT+Ol5P7SfCs5/uGdWUYQEMqOlg6w9R4Pe8d+mk8KGvfE9/zTwGg0nRgKqlQXrWRERv cuEwQbridlPAoQHrFWtwpgYMXx2TaZ3sihcIPo9uU5eBs0rf4mOERY75SK+Ekayv2ucTfjxr Kf014py2aoRJHuvy85ee/zIyLmve5hngZTTe3Wg3TInT9UTFzTPhItam6dZ1xqdTGHZYGU0O otRHcwLGt470grdiob6PfVTXoHlBvkWRadMhSuG4RORCDpq89vu5QralFNIf3EysNohoFy2A LYg2/D53xbU/aa4DDzBb5b1Rkg/udO1gZocVQWrDh6I2K3+cCs7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: sUFW1Uz346IjH1nU3lEBMoWDzH0BmuWs5ue4AwzOmgc_1755871201 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: wireguard@lists.zx2c4.com X-Mailman-Version: 2.1.30rc1 Precedence: list List-Id: Development discussion of WireGuard List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: wireguard-bounces@lists.zx2c4.com Sender: "WireGuard" On 22.08.25 13:32, Pavel Begunkov wrote: > On 8/21/25 21:06, David Hildenbrand wrote: >> We always provide a single dst page, it's unclear why the io_copy_cache >> complexity is required. > > Because it'll need to be pulled outside the loop to reuse the page for > multiple copies, i.e. packing multiple fragments of the same skb into > it. Not finished, and currently it's wasting memory. Okay, so what you're saying is that there will be follow-up work that will actually make this structure useful. > > Why not do as below? Pages there never cross boundaries of their folios. > Do you want it to be taken into the io_uring tree? This should better all go through the MM tree where we actually guarantee contiguous pages within a folio. (see the cover letter) > > diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c > index e5ff49f3425e..18c12f4b56b6 100644 > --- a/io_uring/zcrx.c > +++ b/io_uring/zcrx.c > @@ -975,9 +975,9 @@ static ssize_t io_copy_page(struct io_copy_cache *cc, struct page *src_page, > > if (folio_test_partial_kmap(page_folio(dst_page)) || > folio_test_partial_kmap(page_folio(src_page))) { > - dst_page = nth_page(dst_page, dst_offset / PAGE_SIZE); > + dst_page += dst_offset / PAGE_SIZE; > dst_offset = offset_in_page(dst_offset); > - src_page = nth_page(src_page, src_offset / PAGE_SIZE); > + src_page += src_offset / PAGE_SIZE; Yeah, I can do that in the next version given that you have plans on extending that code soon. -- Cheers David / dhildenb