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Peter Anvin" , Paolo Bonzini , Wanpeng Li , Vitaly Kuznetsov , Andy Lutomirski , Frederic Weisbecker , "Paul E. McKenney" , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Andrew Morton , Uladzislau Rezki , Christoph Hellwig , Lorenzo Stoakes , Josh Poimboeuf , Jason Baron , Kees Cook , Sami Tolvanen , Ard Biesheuvel , Nicholas Piggin , Juerg Haefliger , Nicolas Saenz Julienne , "Kirill A. Shutemov" , Nadav Amit , Dan Carpenter , Chuang Wang , Yang Jihong , Petr Mladek , "Jason A. Donenfeld" , Song Liu , Julian Pidancet , Tom Lendacky , Dionna Glaze , Thomas =?iso-8859-1?Q?Wei=DFschuh?= , Juri Lelli , Marcelo Tosatti , Yair Podemsky , Daniel Wagner Subject: Re: [RFC PATCH v3 13/15] context_tracking,x86: Add infrastructure to defer kernel TLBI Message-ID: <20241209121249.GN35539@noisy.programming.kicks-ass.net> References: <20241119153502.41361-1-vschneid@redhat.com> <20241119153502.41361-14-vschneid@redhat.com> <20241120152216.GM19989@noisy.programming.kicks-ass.net> <20241120153221.GM38972@noisy.programming.kicks-ass.net> <20241121111221.GE24774@noisy.programming.kicks-ass.net> <4b562cd0-7500-4b3a-8f5c-e6acfea2896e@intel.com> <20241121153016.GL39245@noisy.programming.kicks-ass.net> <20241205183111.12dc16b3@mordecai.tesarici.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 652564000F X-Rspamd-Server: rspam12 X-Stat-Signature: mx5w5cqw6r4e6o5iar89jxw8tnsq39aw X-Rspam-User: X-HE-Tag: 1733746386-834721 X-HE-Meta: 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 EdU1uVa2 OXh0lJmh0tRj/VYRk/pDDCpH7KYqhDHVDQqH4jewg6JIwAPwaGIzuGZFxkOSUOelPJsWET4yJTpH697nah+eS0ClAaDRNXdA5PQ82yCNEbyy77zfZhIYH4gASQ2un6qw643ra32tb0L0TbPsAecjhX2wOIqEmVc1qezvE7RLJumqWbevmQ+lJpgZxVlKjq19RM/W+f+l1HVxbDB0imEHnLBO6I1Odt72q08wnZZq+qXeNr2DwkWKhOMfotegBrw3POikjHrOKXGbUpDdUba8urXbeea6DnCRMHreEbkeXdJpRYartG5Yw2WtePQ== 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, Dec 09, 2024 at 01:04:43PM +0100, Valentin Schneider wrote: > > But I wonder what exactly was the original scenario encountered by > > Valentin. I mean, if TLB entry invalidations were necessary to sync > > changes to kernel text after flipping a static branch, then it might be > > less overhead to make a list of affected pages and call INVLPG on them. No; TLB is not involved with text patching (on x86). > > Valentin, do you happen to know? > > So from my experimentation (hackbench + kernel compilation on housekeeping > CPUs, dummy while(1) userspace loop on isolated CPUs), the TLB flushes only > occurred from vunmap() - mainly from all the hackbench threads coming and > going. Right, we have virtually mapped stacks.