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Tue, 20 May 2025 09:59:52 -0700 (PDT) X-Google-Smtp-Source: AGHT+IH9IfWJXFVUh9zlVq3n1AuEKD6UqJhdqI6hkbwqQIr3nDPfW3C8vHTS4HJ61qbW6AJWrPiEAw== X-Received: by 2002:a05:6214:33c7:b0:6f8:ca09:d60f with SMTP id 6a1803df08f44-6f8ca09d764mr183451476d6.10.1747760391869; Tue, 20 May 2025 09:59:51 -0700 (PDT) Received: from x1.local ([85.131.185.92]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6f8b08aed47sm73634666d6.50.2025.05.20.09.59.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 May 2025 09:59:51 -0700 (PDT) Date: Tue, 20 May 2025 12:59:47 -0400 From: Peter Xu To: Alex Williamson Cc: lizhe.67@bytedance.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, muchun.song@linux.dev, David Hildenbrand Subject: Re: [PATCH v3] vfio/type1: optimize vfio_pin_pages_remote() for huge folio Message-ID: References: <20250520070020.6181-1-lizhe.67@bytedance.com> <20250520080719.2862017e.alex.williamson@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250520080719.2862017e.alex.williamson@redhat.com> Hi, Alex, On Tue, May 20, 2025 at 08:07:19AM -0600, Alex Williamson wrote: > Peter, David, if you wouldn't mind double checking the folio usage > here, I'd appreciate it. The underlying assumption used here is that > folios always have physically contiguous pages, so we can increment at > the remainder of the folio_nr_pages() rather than iterate each page. Yes I think so. E.g., there's comment above folio definition too: /** * struct folio - Represents a contiguous set of bytes. * ... * A folio is a physically, virtually and logically contiguous set * of bytes... */ For 1G, I wonder if in the future vfio can also use memfd_pin_folios() internally when possible, e.g. after stumbled on top of a hugetlb folio when filling the batch. Thanks, -- Peter Xu