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Peter Anvin" , Peter Zijlstra , David Rientjes , Igor Mammedov , Prarit Bhargava , "brice.goglin@gmail.com" Subject: RE: [PATCH] x86, sched: Allow NUMA nodes to share an LLC on Intel platforms Thread-Topic: [PATCH] x86, sched: Allow NUMA nodes to share an LLC on Intel platforms Thread-Index: AQHW/zSlzL/JNCz2s0ObNbwCfjAg9apQcJ2A Date: Tue, 9 Feb 2021 23:09:27 +0000 Message-ID: References: <20210209223943.9834-1-alison.schofield@intel.com> In-Reply-To: <20210209223943.9834-1-alison.schofield@intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-product: dlpe-windows dlp-reaction: no-action dlp-version: 11.5.1.3 x-originating-ip: [10.22.254.132] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > +#define X86_BUG_NUMA_SHARES_LLC X86_BUG(25) /* CPU may enumerate an LLC shared by multiple NUMA nodes */ During internal review I wondered why this is a "BUG" rather than a "FEATURE" bit. Apparently, the suggestion for "BUG" came from earlier community discussions. Historically it may have seemed reasonable to say that a cache cannot span NUMA domains. But with more and more things moving off the motherboard and into the socket, this doesn't seem too weird now. -Tony