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[2a00:1028:83b8:1e7a:3010:3bd6:8521:caf1]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47d7f6ef868sm214237245e9.11.2026.01.09.08.54.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Jan 2026 08:54:26 -0800 (PST) Date: Fri, 9 Jan 2026 17:54:23 +0100 From: Petr Tesarik To: Steven Rostedt Cc: Masami Hiramatsu , Mathieu Desnoyers , Sebastian Andrzej Siewior , Clark Williams , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev Subject: Re: [PATCH] ring-buffer: Use a housekeeping CPU to wake up waiters Message-ID: <20260109175423.70ba42d7@mordecai> In-Reply-To: <20260109111506.66ad545a@gandalf.local.home> References: <20260106091039.2012108-1-ptesarik@suse.com> <20260106170405.425f469e@gandalf.local.home> <20260107085009.58fcffd4@mordecai> <20260107105137.4cf9a67e@mordecai> <20260107111709.0d115cd8@gandalf.local.home> <20260107111935.3befc296@gandalf.local.home> <20260108093932.252f6bc7@mordecai> <20260108115800.7a7fc8a7@gandalf.local.home> <20260109095756.13deb429@mordecai> <20260109111506.66ad545a@gandalf.local.home> X-Mailer: Claws Mail 4.3.1 (GTK 3.24.51; x86_64-suse-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 9 Jan 2026 11:15:06 -0500 Steven Rostedt wrote: > On Fri, 9 Jan 2026 09:57:56 +0100 > Petr Tesarik wrote: > > > I have removed both "inline" and "noinline" in v2, leaving it at the > > discretion of the compiler. If you believe it deserves a "noinline", > > feel free to add it. FWIW on x86-64, I didn't observe any measurable > > diference either in latency or instruction cache footprint. > > Please add the noinline. I went through and added strategic "noinline" and > "__always_inline", as well as placing "likely()" and "unlikely()" and > dropped the cost of adding an event from just under 300ns down to less than > 150ns. > > This code is called during function tracing (hit at every function call), > and yes, every little bit helps! I'm going to wait a few days for further comments, then add it in v3. Thanks for your time! Petr T