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Fri, 16 Aug 2024 07:05:47 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id EDDLLUv6vmbJAwAAD6G6ig (envelope-from ); Fri, 16 Aug 2024 07:05:47 +0000 Message-ID: <904a433c-0471-4f11-a34b-cef8adf1663c@suse.de> Date: Fri, 16 Aug 2024 09:05:46 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC] Virtualizing tagged disaggregated memory capacity (app specific, multi host shared) Content-Language: en-US To: Jonathan Cameron , David Hildenbrand , linux-mm@kvack.org, linux-cxl@vger.kernel.org, Davidlohr Bueso , Ira Weiny , John Groves , virtualization@lists.linux.dev Cc: Oscar Salvador , qemu-devel@nongnu.org, Dave Jiang , Dan Williams , linuxarm@huawei.com, wangkefeng.wang@huawei.com, John Groves , Fan Ni , Navneet Singh , =?UTF-8?B?4oCcTWljaGFlbCBTLiBUc2lya2lu4oCd?= , Igor Mammedov , =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= References: <20240815172223.00001ca7@Huawei.com> From: Hannes Reinecke In-Reply-To: <20240815172223.00001ca7@Huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Action: no action X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 4A1DDC0016 X-Stat-Signature: wpg4d585mfajereb5md1schq56xpjg7k X-HE-Tag: 1723791950-760642 X-HE-Meta: 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 B/BZRwPv WAyEyHiaL3cRvdZrCk0xxqo7xryUXFPsqh7MtWA2KeZZlMsCK3uZgGyzFv2vdKBgFkGKBVzVv3wjcx/ePRxHdVbe6M9IAiHQB86zRw28+dBPJTXLeaL5VjDwQ/WVzsV4IYT13jV3Ck8uLSIxkqc+rZOPS4VZe7ejaS22Zs4RFhscjlCMkmv6c2YklrZmpIOnR+ywoBx8aaRbVYDAFipEF+WuWq0K2VFl9oyNxoIQeHjk3kCmIS6dbkGmAyIjzEXHCHHpGvpbhEr7yBU2U3zBvYsefyRZlwmOz5edZCOpSIS/KgViKIhHjLtj9YQ== 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 8/15/24 18:22, Jonathan Cameron wrote: > Introduction > ============ > > If we think application specific memory (including inter-host shared memory) is > a thing, it will also be a thing people want to use with virtual machines, > potentially nested. So how do we present it at the Host to VM boundary? > > This RFC is perhaps premature given we haven't yet merged upstream support for > the bare metal case. However I'd like to get the discussion going given we've > touched briefly on this in a number of CXL sync calls and it is clear no one is > entirely sure what direction make sense. We may briefly touch on this in the > LPC CXL uconf, but time will be very limited. > Thanks for the detailed write-up. Can't we have an ad-hoc meeting at OSS/LPC to gather interested/relevant people to explore ideas around this? In particular I'd be interested on how to _get_ the application specific memory to the application in question. It's easy if you have your own application and design it to work on DAX devices. Obviously this approach won't work for unmodified applications; however, they really might want to use this, too. And, of course, the other mentioned problems are worth discussing, and I do agree that the uconf will probably not providing sufficient time for this. Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich