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[2003:d8:2f2c:5500:988:23f9:faa0:7232]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b4708d0af7sm1973309f8f.35.2025.07.04.01.47.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 04 Jul 2025 01:47:01 -0700 (PDT) Message-ID: <77d99da0-10eb-4a4d-8ad9-c6ec83cb4540@redhat.com> Date: Fri, 4 Jul 2025 10:47:00 +0200 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 5/5] vfio/type1: optimize vfio_unpin_pages_remote() To: lizhe.67@bytedance.com, alex.williamson@redhat.com, akpm@linux-foundation.org, peterx@redhat.com, jgg@ziepe.ca Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20250704062602.33500-1-lizhe.67@bytedance.com> <20250704062602.33500-6-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: <20250704062602.33500-6-lizhe.67@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 04.07.25 08:26, 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. > > It would be very rare for reserved PFNs and non reserved will to be mixed > within the same range. So this patch utilizes the has_rsvd variable > introduced in the previous patch to determine whether batch put_pfn() > operations can be performed. Moreover, compared to put_pfn(), > unpin_user_page_range_dirty_lock() is capable of handling large folio > scenarios more efficiently. > > The performance test results for completing the 16G VFIO IOMMU DMA > unmapping are as follows. > > Base(v6.16-rc4): > ./vfio-pci-mem-dma-map 0000:03:00.0 16 > ------- AVERAGE (MADV_HUGEPAGE) -------- > VFIO UNMAP DMA in 0.135 s (118.6 GB/s) > ------- AVERAGE (MAP_POPULATE) -------- > VFIO UNMAP DMA in 0.312 s (51.3 GB/s) > ------- AVERAGE (HUGETLBFS) -------- > VFIO UNMAP DMA in 0.136 s (117.3 GB/s) > > With this patchset: > ------- AVERAGE (MADV_HUGEPAGE) -------- > VFIO UNMAP DMA in 0.045 s (357.0 GB/s) > ------- AVERAGE (MAP_POPULATE) -------- > VFIO UNMAP DMA in 0.288 s (55.6 GB/s) > ------- AVERAGE (HUGETLBFS) -------- > VFIO UNMAP DMA in 0.045 s (353.9 GB/s) > > For large folio, we achieve an over 66% performance improvement in > the VFIO UNMAP DMA item. For small folios, the performance test > results appear to show a slight improvement. > > Suggested-by: Jason Gunthorpe > Signed-off-by: Li Zhe > --- > drivers/vfio/vfio_iommu_type1.c | 20 ++++++++++++++++---- > 1 file changed, 16 insertions(+), 4 deletions(-) > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index 13c5667d431c..3971539b0d67 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -792,17 +792,29 @@ static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr, > return pinned; > } > > +static inline void put_valid_unreserved_pfns(unsigned long start_pfn, > + unsigned long npage, int prot) > +{ > + unpin_user_page_range_dirty_lock(pfn_to_page(start_pfn), npage, > + prot & IOMMU_WRITE); > +} > + > static long vfio_unpin_pages_remote(struct vfio_dma *dma, dma_addr_t iova, > unsigned long pfn, unsigned long npage, > 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++; > + if (dma->has_rsvd) { > + long i; No need to move "long i" here, but also doesn't really matter. > > + for (i = 0; i < npage; i++) > + if (put_pfn(pfn++, dma->prot)) > + unlocked++; > + } else { > + put_valid_unreserved_pfns(pfn, npage, dma->prot); > + unlocked = npage; > + } > if (do_accounting) > vfio_lock_acct(dma, locked - unlocked, true); > Reviewed-by: David Hildenbrand -- Cheers, David / dhildenb