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charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: dmgptxprykxn4bz54ir9t8niprdu4oaa X-Rspamd-Queue-Id: 3748A180018 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1722868901-393138 X-HE-Meta: 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 sfW4M0A7 Wi72gzbo7n7y7jVlMCQu1xEe6zGzQ9ZbBMmBOPzwUefacSvuGlfwpQHte5JX9FifZ6mNUobqaEEpZMgati/taKTKZWjdnq0aDi511zaDItIz7HwtH19ZIaRtXp4A9FZKvx5Cus9LJPyBDtM/4zKEzcgOTgA5wN26ih/1A9rD3Ij/65AyDUDXU6JUwRQrg4klpCo8tuc5L4bbdu/lOT6YJ64wK/SyVXuRiNpOj X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Aug 5, 2024 at 4:35=E2=80=AFPM Theodore Ts'o wrote: > On Mon, Aug 05, 2024 at 11:32:35AM +0200, James Gowans wrote: > > Guestmemfs implements preservation acrosss kexec by carving out a > > large contiguous block of host system RAM early in boot which is > > then used as the data for the guestmemfs files. > > Also, the VMM update process is not a common case thing, so we don't > need to optimize for performance. If we need to temporarily use > swap/zswap to allocate memory at VMM update time, and if the pages > aren't contiguous when they are copied out before doing the VMM > update I'm not sure I understand, where would this temporary allocation happen? > that might be very well worth the vast of of memory needed to > pay for reserving memory on the host for the VMM update that only > might happen once every few days/weeks/months (depending on whether > you are doing update just for high severity security fixes, or for > random VMM updates). > > Even if you are updating the VMM every few days, it still doesn't seem > that permanently reserving contiguous memory on the host can be > justified from a TCO perspective. As far as I understand, this is intended for use in systems that do not do anything except hosting VMs, where anyway you'd devote 90%+ of host memory to hugetlbfs gigapages. Paolo