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X-CSE-ConnectionGUID: Ovpr0SPyRAq2eK6TYIIwEA== X-CSE-MsgGUID: FvDk8wgxS/KpzXaPDplHUw== X-IronPort-AV: E=McAfee;i="6700,10204,11222"; a="47717862" X-IronPort-AV: E=Sophos;i="6.11,199,1725346800"; d="scan'208";a="47717862" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by orvoesa102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Nov 2024 12:39:24 -0700 X-CSE-ConnectionGUID: OHnYS5S6TcuNT3OY7OKdwA== X-CSE-MsgGUID: 2dJ9/DffSeuFoRFq5NBtZA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.11,250,1725346800"; d="scan'208";a="87583065" Received: from ccbilbre-mobl3.amr.corp.intel.com (HELO [10.124.220.146]) ([10.124.220.146]) by fmviesa005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Nov 2024 12:39:22 -0700 Message-ID: <4a015283-28e2-4459-825a-1fd542b81110@intel.com> Date: Fri, 1 Nov 2024 12:39:21 -0700 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v3 0/6] Direct Map Removal for guest_memfd To: "Manwaring, Derek" Cc: ackerleytng@google.com, agordeev@linux.ibm.com, aou@eecs.berkeley.edu, borntraeger@linux.ibm.com, bp@alien8.de, canellac@amazon.at, catalin.marinas@arm.com, chenhuacai@kernel.org, corbet@lwn.net, dave.hansen@linux.intel.com, david@redhat.com, elena.reshetova@intel.com, gerald.schaefer@linux.ibm.com, gor@linux.ibm.com, graf@amazon.com, hca@linux.ibm.com, hpa@zytor.com, jgowans@amazon.com, jthoughton@google.com, kalyazin@amazon.com, kernel@xen0n.name, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-trace-kernel@vger.kernel.org, loongarch@lists.linux.dev, luto@kernel.org, mathieu.desnoyers@efficios.com, mhiramat@kernel.org, mingo@redhat.com, mlipp@amazon.at, palmer@dabbelt.com, paul.walmsley@sifive.com, pbonzini@redhat.com, peterz@infradead.org, quic_eberman@quicinc.com, rostedt@goodmis.org, roypat@amazon.co.uk, rppt@kernel.org, seanjc@google.com, shuah@kernel.org, svens@linux.ibm.com, tabba@google.com, tglx@linutronix.de, vannapurve@google.com, will@kernel.org, x86@kernel.org, xmarcalx@amazon.com References: <71e9b2c8-0cc4-4646-88f0-7780e108e610@amazon.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/1/24 12:29, Manwaring, Derek wrote: > As far as performance, are you talking about just the fracturing or > something beyond that? The data Mike brought to LSFMMBPF 2023 showed the > perf impact from direct map fragmentation for memfd_secret isn't "that > bad" [1]. Just the fracturing. Mike's data are interesting, but I still think we're pretty far away from saying that the kernel doesn't need large mappings.