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[195.250.132.146]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a013d08f1esm6313585e9.4.2026.09.29.06.54.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Sep 2026 06:54:03 -0700 (PDT) Date: Tue, 29 Sep 2026 15:54:01 +0200 From: Petr Mladek To: Sang-Heon Jeon Cc: John Ogness , linux-kernel@vger.kernel.org, Sergey Senozhatsky , Steven Rostedt Subject: Re: [PATCH v2] printk: increase the ring buffer for more than 16 CPUs by default Message-ID: References: <20260927091756.50831-1-ekffu200098@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260927091756.50831-1-ekffu200098@gmail.com> On Sun 2026-09-27 18:17:54, Sang-Heon Jeon wrote: > The default LOG_BUF_SHIFT is 17, which means 128 KB, and > LOG_CPU_MAX_BUF_SHIFT is 12, which means 4 KB per CPU. > > By default the ring buffer is increased when > (num_possible_cpus() - 1) * 4 KB > 64 KB, which requires more than 17 > CPUs. > > Remove the explicit subtraction of one, so the ring buffer is increased > for more than 16 CPUs, which is a power of two. Also fix the outdated > comment. > > Suggested-by: Petr Mladek > Signed-off-by: Sang-Heon Jeon Looks good to me: Reviewed-by: Petr Mladek Best Regards, Petr