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X-CSE-ConnectionGUID: TgvWkDpJRr2MdRR7QYZ6gQ== X-CSE-MsgGUID: rEqQ1yTAQ1SVtdkDXJp5CA== X-IronPort-AV: E=McAfee;i="6700,10204,11399"; a="71071412" X-IronPort-AV: E=Sophos;i="6.15,200,1739865600"; d="scan'208";a="71071412" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by fmvoesa101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Apr 2025 08:24:16 -0700 X-CSE-ConnectionGUID: djvQwLdiSIOUrXyaz6HO3w== X-CSE-MsgGUID: GE/MdNfoTNa8pIrfVyB5NQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.15,200,1739865600"; d="scan'208";a="151793818" Received: from sramkris-mobl1.amr.corp.intel.com (HELO [10.124.220.195]) ([10.124.220.195]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Apr 2025 08:24:14 -0700 Message-ID: <0770a3d4-c8ff-4172-9eda-c9debfee6d03@intel.com> Date: Wed, 9 Apr 2025 08:24:11 -0700 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 09/14] x86: Minimal SLAB alignment To: Maciej Wieczor-Retman Cc: hpa@zytor.com, hch@infradead.org, nick.desaulniers+lkml@gmail.com, kuan-ying.lee@canonical.com, masahiroy@kernel.org, samuel.holland@sifive.com, mingo@redhat.com, corbet@lwn.net, ryabinin.a.a@gmail.com, guoweikang.kernel@gmail.com, jpoimboe@kernel.org, ardb@kernel.org, vincenzo.frascino@arm.com, glider@google.com, kirill.shutemov@linux.intel.com, apopple@nvidia.com, samitolvanen@google.com, kaleshsingh@google.com, jgross@suse.com, andreyknvl@gmail.com, scott@os.amperecomputing.com, tony.luck@intel.com, dvyukov@google.com, pasha.tatashin@soleen.com, ziy@nvidia.com, broonie@kernel.org, gatlin.newhouse@gmail.com, jackmanb@google.com, wangkefeng.wang@huawei.com, thiago.bauermann@linaro.org, tglx@linutronix.de, kees@kernel.org, akpm@linux-foundation.org, jason.andryuk@amd.com, snovitoll@gmail.com, xin@zytor.com, jan.kiszka@siemens.com, bp@alien8.de, rppt@kernel.org, peterz@infradead.org, pankaj.gupta@amd.com, thuth@redhat.com, andriy.shevchenko@linux.intel.com, joel.granados@kernel.org, kbingham@kernel.org, nicolas@fjasle.eu, mark.rutland@arm.com, surenb@google.com, catalin.marinas@arm.com, morbo@google.com, justinstitt@google.com, ubizjak@gmail.com, jhubbard@nvidia.com, urezki@gmail.com, dave.hansen@linux.intel.com, bhe@redhat.com, luto@kernel.org, baohua@kernel.org, nathan@kernel.org, will@kernel.org, brgerst@gmail.com, llvm@lists.linux.dev, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, x86@kernel.org References: <173d99afea37321e76e9380b49bd5966be8db849.1743772053.git.maciej.wieczor-retman@intel.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/9/25 05:49, Maciej Wieczor-Retman wrote: > The differences looked mostly like noise, sometimes the higher alignment would > use up a little bit less memory, sometimes a little bit more. I looked at all > values in "cat /proc/meminfo". > > Is there some slab/slub benchmark for the kernel that would make sense to > checkout here? You don't need to benchmark anything. Just mention that it will waste memory and also give *some* ballpark estimate on how much. Just looking at your laptop's /proc/slabinfo would be a good start. Oh, and it wouldn't hurt to find out when and why the minimal slab alignment got dropped down to 8 bytes. I _thought_ it was higher at some point. Presumably there was a good reason for it and you're now undoing part of it.