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[109.164.254.58]) by smtp.gmail.com with ESMTPSA id bq7-20020a05622a1c0700b00344cb66b860sm1265238qtb.38.2022.08.26.07.32.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 26 Aug 2022 07:32:17 -0700 (PDT) Message-ID: Date: Fri, 26 Aug 2022 16:32:15 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [RFC PATCH 2/2] kvm/kvm-all.c: listener should delay kvm_vm_ioctl to the commit phase Content-Language: en-US To: David Hildenbrand , qemu-devel@nongnu.org Cc: Paolo Bonzini , "Michael S. Tsirkin" , Cornelia Huck , Peter Xu , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Maxim Levitsky , kvm@vger.kernel.org References: <20220816101250.1715523-1-eesposit@redhat.com> <20220816101250.1715523-3-eesposit@redhat.com> <6cb75197-1d9e-babd-349a-3e56b3482620@redhat.com> From: Emanuele Giuseppe Esposito In-Reply-To: <6cb75197-1d9e-babd-349a-3e56b3482620@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Am 26/08/2022 um 16:15 schrieb David Hildenbrand: > On 16.08.22 12:12, Emanuele Giuseppe Esposito wrote: >> Instead of sending a single ioctl every time ->region_* or ->log_* >> callbacks are called, "queue" all memory regions in a list that will >> be emptied only when committing. >> > > Out of interest, how many such regions does the ioctl support? As many > as KVM theoretically supports? (32k IIRC) > I assume you mean for the new ioctl, but yes that's a good question. The problem here is that we could have more than a single update per memory region. So we are not limited anymore to the number of regions, but the number of operations * number of region. I was thinking, maybe when pre-processing QEMU could divide a single transaction into multiple atomic operations (ie operations on the same memory region)? That way avoid sending a single ioctl with 32k * #operation elements. Is that what you mean? Emanuele