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[142.167.56.70]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4ab575ca629sm44704861cf.59.2025.07.16.06.51.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Jul 2025 06:51:58 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1uc2Y9-0000000946K-3xvb; Wed, 16 Jul 2025 10:51:57 -0300 Date: Wed, 16 Jul 2025 10:51:57 -0300 From: Jason Gunthorpe To: Keith Busch Cc: Keith Busch , alex.williamson@redhat.com, kvm@vger.kernel.org, linux-pci@vger.kernel.org, paulmck@kernel.org Subject: Re: [PATCHv2] vfio/type1: conditional rescheduling while pinning Message-ID: <20250716135157.GA2138419@ziepe.ca> References: <20250715184622.3561598-1-kbusch@meta.com> <20250716123201.GA2135755@ziepe.ca> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Jul 16, 2025 at 07:47:04AM -0600, Keith Busch wrote: > On Wed, Jul 16, 2025 at 09:32:01AM -0300, Jason Gunthorpe wrote: > > > > You should be making a matching change to iommufd too.. > > Yeah, okay. My colleauge I've been working with on this hasn't yet > reported CPU stalls using iommufd though, so I'm not sure which path > iommufd takes to know where to place cond_resched(). Blindly stumbly > through it, my best guess right now is arriving at the loop in > iopt_fill_domains_pages(), called through iommufd_vfio_map_dma(). Am I > close? Yeah, I would guess maybe put it in pfn_reader_next() But iommufd won't be faulting the MMIO memory from VFIO so you can't hit the same exact condition you are describing.. Jason