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Peter Anvin" , Thomas Huth , Sean Christopherson , Jisheng Zhang , Alexandre Ghiti , Christian Borntraeger , Sven Schnelle Subject: Re: [PATCH v5 8/8] futex: Use runtime constants for __futex_hash() hot path Message-ID: <20260701084150.GNOeboLw@linutronix.de> References: <20260630045531.3939-1-kprateek.nayak@amd.com> <20260630045531.3939-9-kprateek.nayak@amd.com> <20260701075714.GP48970@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260701075714.GP48970@noisy.programming.kicks-ass.net> On 2026-07-01 09:57:14 [+0200], Peter Zijlstra wrote: > The big $1M question: does it actually make it go faster? The whole > point here was performance, right? But I'm not seeing numbers showing > how awesome these patches are. I did complain about the about the size of __futex_data which is blown on distro kernels due to CONFIG_NODES_SHIFT=10 on Debian for instance. This makes it go away at no extra price but yeah let me boot a big box and see. If the performance remains unchanged it is still worth considering due to size savings on the average box with 1 node. The biggest box I have access to has four nodes. If I remember correctly, Prateek was saying that AMD has "normal" boxes which would require =9 for normal operation and they do run distro kernels so lowering that value is not an option. Sebastian