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[2003:d8:2f38:1d00:657c:2aac:ecf5:5df8]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-454b161fb78sm103469475e9.1.2025.07.07.00.29.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 07 Jul 2025 00:29:31 -0700 (PDT) Message-ID: <9d74e93d-5a5f-4ffa-91fa-eb2061080f94@redhat.com> Date: Mon, 7 Jul 2025 09:29:30 +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 2/5] vfio/type1: optimize vfio_pin_pages_remote() To: lizhe.67@bytedance.com, alex.williamson@redhat.com, akpm@linux-foundation.org, jgg@ziepe.ca, peterx@redhat.com Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20250707064950.72048-1-lizhe.67@bytedance.com> <20250707064950.72048-3-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: <20250707064950.72048-3-lizhe.67@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 07.07.25 08:49, lizhe.67@bytedance.com wrote: > From: Li Zhe > > When vfio_pin_pages_remote() is called with a range of addresses that > includes large folios, the function currently performs individual > statistics counting operations for each page. This can lead to significant > performance overheads, especially when dealing with large ranges of pages. > Batch processing of statistical counting operations can effectively enhance > performance. > > In addition, the pages obtained through longterm GUP are neither invalid > nor reserved. Therefore, we can reduce the overhead associated with some > calls to function is_invalid_reserved_pfn(). > > The performance test results for completing the 16G VFIO IOMMU DMA mapping > are as follows. > > Base(v6.16-rc4): > ------- AVERAGE (MADV_HUGEPAGE) -------- > VFIO MAP DMA in 0.047 s (340.2 GB/s) > ------- AVERAGE (MAP_POPULATE) -------- > VFIO MAP DMA in 0.280 s (57.2 GB/s) > ------- AVERAGE (HUGETLBFS) -------- > VFIO MAP DMA in 0.052 s (310.5 GB/s) > > With this patch: > ------- AVERAGE (MADV_HUGEPAGE) -------- > VFIO MAP DMA in 0.027 s (602.1 GB/s) > ------- AVERAGE (MAP_POPULATE) -------- > VFIO MAP DMA in 0.257 s (62.4 GB/s) > ------- AVERAGE (HUGETLBFS) -------- > VFIO MAP DMA in 0.031 s (517.4 GB/s) > > For large folio, we achieve an over 40% performance improvement. > For small folios, the performance test results indicate a > slight improvement. > > Signed-off-by: Li Zhe > Co-developed-by: Alex Williamson > Signed-off-by: Alex Williamson > --- > drivers/vfio/vfio_iommu_type1.c | 83 ++++++++++++++++++++++++++++----- > 1 file changed, 71 insertions(+), 12 deletions(-) > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index 1136d7ac6b59..03fce54e1372 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -318,7 +318,13 @@ static void vfio_dma_bitmap_free_all(struct vfio_iommu *iommu) > /* > * Helper Functions for host iova-pfn list > */ > -static struct vfio_pfn *vfio_find_vpfn(struct vfio_dma *dma, dma_addr_t iova) > + > +/* > + * Find the highest vfio_pfn that overlapping the range > + * [iova_start, iova_end) in rb tree. > + */ > +static struct vfio_pfn *vfio_find_vpfn_range(struct vfio_dma *dma, > + dma_addr_t iova_start, dma_addr_t iova_end) > { > struct vfio_pfn *vpfn; > struct rb_node *node = dma->pfn_list.rb_node; > @@ -326,9 +332,9 @@ static struct vfio_pfn *vfio_find_vpfn(struct vfio_dma *dma, dma_addr_t iova) > while (node) { > vpfn = rb_entry(node, struct vfio_pfn, node); > > - if (iova < vpfn->iova) > + if (iova_end <= vpfn->iova) > node = node->rb_left; > - else if (iova > vpfn->iova) > + else if (iova_start > vpfn->iova) > node = node->rb_right; > else > return vpfn; > @@ -336,6 +342,11 @@ static struct vfio_pfn *vfio_find_vpfn(struct vfio_dma *dma, dma_addr_t iova) > return NULL; > } > > +static inline struct vfio_pfn *vfio_find_vpfn(struct vfio_dma *dma, dma_addr_t iova) > +{ > + return vfio_find_vpfn_range(dma, iova, iova + PAGE_SIZE); > +} > + > static void vfio_link_pfn(struct vfio_dma *dma, > struct vfio_pfn *new) > { > @@ -614,6 +625,39 @@ static long vaddr_get_pfns(struct mm_struct *mm, unsigned long vaddr, > return ret; > } > > + > +static long vpfn_pages(struct vfio_dma *dma, > + dma_addr_t iova_start, long nr_pages) > +{ > + dma_addr_t iova_end = iova_start + (nr_pages << PAGE_SHIFT); > + struct vfio_pfn *top = vfio_find_vpfn_range(dma, iova_start, iova_end); > + long ret = 1; > + struct vfio_pfn *vpfn; > + struct rb_node *prev; > + struct rb_node *next; > + > + if (likely(!top)) > + return 0; > + > + prev = next = &top->node; > + > + while ((prev = rb_prev(prev))) { > + vpfn = rb_entry(prev, struct vfio_pfn, node); > + if (vpfn->iova < iova_start) > + break; > + ret++; > + } > + > + while ((next = rb_next(next))) { > + vpfn = rb_entry(next, struct vfio_pfn, node); > + if (vpfn->iova >= iova_end) > + break; > + ret++; > + } > + > + return ret; > +} > + > /* > * Attempt to pin pages. We really don't want to track all the pfns and > * the iommu can only map chunks of consecutive pfns anyway, so get the > @@ -680,32 +724,47 @@ static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr, > * and rsvd here, and therefore continues to use the batch. > */ > while (true) { > + long nr_pages, acct_pages = 0; > + > if (pfn != *pfn_base + pinned || > rsvd != is_invalid_reserved_pfn(pfn)) > goto out; > > + /* > + * Using GUP with the FOLL_LONGTERM in > + * vaddr_get_pfns() will not return invalid > + * or reserved pages. > + */ > + nr_pages = num_pages_contiguous( > + &batch->pages[batch->offset], > + batch->size); > + if (!rsvd) { > + acct_pages = nr_pages; > + acct_pages -= vpfn_pages(dma, iova, nr_pages); > + } > + > /* > * Reserved pages aren't counted against the user, > * externally pinned pages are already counted against > * the user. > */ > - if (!rsvd && !vfio_find_vpfn(dma, iova)) { > + if (acct_pages) { > if (!dma->lock_cap && > - mm->locked_vm + lock_acct + 1 > limit) { > + mm->locked_vm + lock_acct + acct_pages > limit) { Weird indentation change. It should be if (!dma->lock_cap && mm->locked_vm + lock_acct + acct_pages > limit) { ^ aligned here Please don't drop acks/rbs already given in previous submissions. Acked-by: David Hildenbrand -- Cheers, David / dhildenb