From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C864E20E01F for ; Mon, 16 Jun 2025 08:14:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750061671; cv=none; b=ehDePQ/pWK7s7zJT8XYxTD6amveWEkjD7oNV2R9s2wUXBJZPAWk31t0Htt7A7a0d3f4WNnZ9ssY4lYDpIaDdKtnkbsCxwr9kuYlv1FxLB8VuMsGjjIsiocgIlZlu8hmS0cfRTUnRFubcne1ubdlofSJlJUarFehvrVtEugCcm3Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750061671; c=relaxed/simple; bh=sXbpD+2mS3DOGvWusrR+Jf100oeAqn3Tv624kzTT35Q=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=qGJH/R8ktanNEgyAY53OKjKpJP0qN7tRmx34vowMI90c4IX7WENiDqytw3tAMnbZspFfACMTIxgh9LxFR4y0EhJlQk7WcBAOa4DbTdVC3FZDtwyacaTmr+A5vJSxZHpwu+e0bbLEOFPs16/5fhRgHILID4gXG4IDYeTqz11z++Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=RNTcYCb0; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="RNTcYCb0" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1750061668; 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=Z9d5nT3dLn4tYGNwfTweExyDusfLZutzgl25vcl/liw=; b=RNTcYCb0xwErjJHlXQwPzsGmpi8RV9Ji0MhJH1CmAibDkVqohYtQMEvkGfiAyc8cI4taLA 26De21IRb2yC9HvDprje9mstEEhMifOLrjm7jyJ13SHc3t9HFzY0q2NJ1laydTYXwoVebp cJHdmXzqyiSAgFP2R2dFXrXJtfbF72s= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-588-QkSXMnW0O0qPKNKQYH69jA-1; Mon, 16 Jun 2025 04:14:27 -0400 X-MC-Unique: QkSXMnW0O0qPKNKQYH69jA-1 X-Mimecast-MFC-AGG-ID: QkSXMnW0O0qPKNKQYH69jA_1750061666 Received: by mail-wm1-f69.google.com with SMTP id 5b1f17b1804b1-452ff9e054eso21950115e9.2 for ; Mon, 16 Jun 2025 01:14:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1750061666; x=1750666466; h=content-transfer-encoding:in-reply-to:organization: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=Z9d5nT3dLn4tYGNwfTweExyDusfLZutzgl25vcl/liw=; b=lBXR87c2vRQxt4jwiulCPwm7d0A0nbXt3Z6L/z3Z0UUbQYbRb/wOYxGtr1FTKfN/mC nyCQSIj+JwlHGsLjbPox68s+p3tV33eFsu1Umvd3l1fMP0JDCakqy7DBRngjjfomI/+G S5KrELdPOA6cfV3BF8JLCSsz6R85SH+PjQayyHjyQNiMU6h3NaDemKh+1bmx+FzEtKYC 7/REBGAMaqzvWQteJsE/yVApvsRqzMdREdpQ0ig9quM0SSiHqfF2FHsrhC8pR+daapMa K2igoKKIzPLZCrKNARc9HSBZki9umS/PySg9CwBrAh+dj4dJRHEG6jTNYdnOf4e7yBJs qHYw== X-Forwarded-Encrypted: i=1; AJvYcCUNdvrwkfQN5NY88R7k4g3QxUwX3fYpQeXjV7YaDB6OpQ+Fz80UMTkbF9nOPqiLAircbLM7OlAG/v6hygo=@vger.kernel.org X-Gm-Message-State: AOJu0YyoaV19yHu+ZyfjqXow7izRdgoO6O8NuJAdMVomsp69f30rdk7h Y8gPlyC4lsylfUSD2TJRF8RJNSF+nR+tf01jHNR+2lubjkqq5lWM4Pw5YYB3NoF89AdioPNk9Im +letbn45ujUnRZ03A8AgOKhHj4asZphAyw8bEbWSTavB3rDEJfMpu5vd7f6AcrcT+ow== X-Gm-Gg: ASbGncsfwd9Om37wknXsampEqFnNteJj1bsKDv8YpErLSY4M9GmWVIz7mbApA7be1wE 9SMFFVte67lmCMHG7yXSszFhPEuPV0C92b/GpZWU1zQltctwRaQK8TNIILIfhqOQGn0KmMHdT+u P4kWGrlBpBAZcqjrJgljZb58nTqU5n8lxL4m86NEJJK3WvlSK5EFjZIa871/RXeXy7HqmSZ8o+O lcM7ZwBTR6x8T2B9i5TJWunCT46h+XWCqfTA5e/oh19X3DcQYFJbXFuEAO/nZNeH7pScIDd1KLL sEuFvq2WR6bb2K36Xhm3mhi03g0iptCQJ233MzzWmMhiHDBzZ/XIQad1CQ3eG7CIeCinm7sDD1c FK2HIbmmm3mnXy7z3Zy+A4XOTVfpWX2NPITqY82wa7J32oBg= X-Received: by 2002:a05:600c:a410:b0:450:cc79:676 with SMTP id 5b1f17b1804b1-4533cc0305fmr55799225e9.20.1750061665602; Mon, 16 Jun 2025 01:14:25 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHwVtehWD9EMTXrohOPXE/HZxJShoL5xuQB7InTk8lIP2sBgiHefn7LmOqHVAdbPXP9oK3DaQ== X-Received: by 2002:a05:600c:a410:b0:450:cc79:676 with SMTP id 5b1f17b1804b1-4533cc0305fmr55799065e9.20.1750061665197; Mon, 16 Jun 2025 01:14:25 -0700 (PDT) Received: from ?IPV6:2003:d8:2f25:bd00:949:b5a9:e02a:f265? (p200300d82f25bd000949b5a9e02af265.dip0.t-ipconnect.de. [2003:d8:2f25:bd00:949:b5a9:e02a:f265]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4532e261a72sm135903195e9.38.2025.06.16.01.14.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Jun 2025 01:14:24 -0700 (PDT) Message-ID: <753caff4-58d6-4d23-ae69-4b909a99aa16@redhat.com> Date: Mon, 16 Jun 2025 10:14:23 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/2] vfio/type1: optimize vfio_unpin_pages_remote() for large folio To: lizhe.67@bytedance.com, alex.williamson@redhat.com Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, peterx@redhat.com References: <20250616075251.89067-1-lizhe.67@bytedance.com> <20250616075251.89067-3-lizhe.67@bytedance.com> From: David Hildenbrand Content-Language: en-US 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 ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20250616075251.89067-3-lizhe.67@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 16.06.25 09:52, lizhe.67@bytedance.com wrote: > From: Li Zhe > > When vfio_unpin_pages_remote() is called with a range of addresses that > includes large folios, the function currently performs individual > put_pfn() operations for each page. This can lead to significant > performance overheads, especially when dealing with large ranges of pages. > > This patch optimize this process by batching the put_pfn() operations. > > The performance test results, based on v6.15, for completing the 16G VFIO > IOMMU DMA unmapping, obtained through unit test[1] with slight > modifications[2], are as follows. > > Base(v6.15): > ./vfio-pci-mem-dma-map 0000:03:00.0 16 > ------- AVERAGE (MADV_HUGEPAGE) -------- > VFIO MAP DMA in 0.047 s (338.6 GB/s) > VFIO UNMAP DMA in 0.138 s (116.2 GB/s) > ------- AVERAGE (MAP_POPULATE) -------- > VFIO MAP DMA in 0.280 s (57.2 GB/s) > VFIO UNMAP DMA in 0.312 s (51.3 GB/s) > ------- AVERAGE (HUGETLBFS) -------- > VFIO MAP DMA in 0.052 s (308.3 GB/s) > VFIO UNMAP DMA in 0.139 s (115.1 GB/s) > > Map[3] + This patchset: > ------- AVERAGE (MADV_HUGEPAGE) -------- > VFIO MAP DMA in 0.027 s (598.2 GB/s) > VFIO UNMAP DMA in 0.049 s (328.7 GB/s) > ------- AVERAGE (MAP_POPULATE) -------- > VFIO MAP DMA in 0.289 s (55.3 GB/s) > VFIO UNMAP DMA in 0.303 s (52.9 GB/s) > ------- AVERAGE (HUGETLBFS) -------- > VFIO MAP DMA in 0.032 s (506.8 GB/s) > VFIO UNMAP DMA in 0.049 s (326.7 GB/s) > > For large folio, we achieve an approximate 64% performance improvement > in the VFIO UNMAP DMA item. For small folios, the performance test > results appear to show no significant changes. > > [1]: https://github.com/awilliam/tests/blob/vfio-pci-mem-dma-map/vfio-pci-mem-dma-map.c > [2]: https://lore.kernel.org/all/20250610031013.98556-1-lizhe.67@bytedance.com/ > [3]: https://lore.kernel.org/all/20250529064947.38433-1-lizhe.67@bytedance.com/ > > Signed-off-by: Li Zhe > --- > drivers/vfio/vfio_iommu_type1.c | 55 +++++++++++++++++++++++++++------ > 1 file changed, 46 insertions(+), 9 deletions(-) > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index e952bf8bdfab..09ecc546ece8 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -469,17 +469,28 @@ static bool is_invalid_reserved_pfn(unsigned long pfn) > return true; > } > > -static int put_pfn(unsigned long pfn, int prot) > +static inline void _put_pfns(struct page *page, int npages, int prot) > { > - if (!is_invalid_reserved_pfn(pfn)) { > - struct page *page = pfn_to_page(pfn); > + unpin_user_page_range_dirty_lock(page, npages, prot & IOMMU_WRITE); > +} > > - unpin_user_pages_dirty_lock(&page, 1, prot & IOMMU_WRITE); > - return 1; > +/* > + * The caller must ensure that these npages PFNs belong to the same folio. > + */ > +static inline int put_pfns(unsigned long pfn, int npages, int prot) > +{ > + if (!is_invalid_reserved_pfn(pfn)) { > + _put_pfns(pfn_to_page(pfn), npages, prot); > + return npages; > } > return 0; > } > > +static inline int put_pfn(unsigned long pfn, int prot) > +{ > + return put_pfns(pfn, 1, prot); > +} > + > #define VFIO_BATCH_MAX_CAPACITY (PAGE_SIZE / sizeof(struct page *)) > > static void __vfio_batch_init(struct vfio_batch *batch, bool single) > @@ -806,11 +817,37 @@ static long vfio_unpin_pages_remote(struct vfio_dma *dma, dma_addr_t iova, > bool do_accounting) > { > long unlocked = 0, locked = vpfn_pages(dma, iova, npage); > - long i; > > - for (i = 0; i < npage; i++) > - if (put_pfn(pfn++, dma->prot)) > - unlocked++; > + while (npage) { > + long nr_pages = 1; > + > + if (!is_invalid_reserved_pfn(pfn)) { > + struct page *page = pfn_to_page(pfn); > + struct folio *folio = page_folio(page); > + long folio_pages_num = folio_nr_pages(folio); > + > + /* > + * For a folio, it represents a physically > + * contiguous set of bytes, and all of its pages > + * share the same invalid/reserved state. > + * > + * Here, our PFNs are contiguous. Therefore, if we > + * detect that the current PFN belongs to a large > + * folio, we can batch the operations for the next > + * nr_pages PFNs. > + */ > + if (folio_pages_num > 1) > + nr_pages = min_t(long, npage, > + folio_pages_num - > + folio_page_idx(folio, page)); > + > + _put_pfns(page, nr_pages, dma->prot); This is sneaky. You interpret the page pointer a an actual page array, assuming that it would give you the right values when advancing nr_pages in that array. This is mostly true, but with !CONFIG_SPARSEMEM_VMEMMAP it is not universally true for very large folios (e.g., in a 1 GiB hugetlb folio when we cross the 128 MiB mark on x86). Not sure if that could already trigger here, but it is subtle. > + unlocked += nr_pages; We could do slightly better here, as we already have the folio. We would add a unpin_user_folio_dirty_locked() similar to unpin_user_folio(). Instead of _put_pfns, we would be calling unpin_user_folio_dirty_locked(folio, nr_pages, dma->prot & IOMMU_WRITE); Then, also what I mention above would not apply. -- Cheers, David / dhildenb