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a="159006914" X-IronPort-AV: E=Sophos;i="5.79,375,1602572400"; d="scan'208";a="159006914" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jan 2021 17:04:01 -0800 IronPort-SDR: JutY4+suLQHZa7SNj+eZqBGXvRtqfQtR30Lls+ca/UF1V5YuBwkervdMEyycpgIdeOIP7ZqU5Y B+2ngbqmBfow== X-IronPort-AV: E=Sophos;i="5.79,375,1602572400"; d="scan'208";a="361760790" Received: from stalawai-desk.amr.corp.intel.com (HELO [10.254.124.248]) ([10.254.124.248]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jan 2021 17:04:01 -0800 Subject: Re: [PATCH] x86/mm: Tracking linear mapping split events since boot To: Tejun Heo Cc: Saravanan D , x86@kernel.org, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, linux-kernel@vger.kernel.org, kernel-team@fb.com References: <30752f8e-16e9-d093-e6ec-31fd45715e9d@intel.com> <0d402da9-d7a2-a3b4-eb6f-bd1b768b3a85@intel.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/25/21 4:53 PM, Tejun Heo wrote: >> This would be a lot more useful if you could reset the counters. Then >> just reset them from userspace at boot. Adding read-write debugfs >> exports for these should be pretty trivial. > While this would work for hands-on cases, I'm a bit worried that this might > be more challenging to gain confidence in large production environments. Which part? Large production environments don't trust data from debugfs? Or don't trust it if it might have been reset? You could stick the "reset" switch in debugfs, and dump something out in dmesg like we do for /proc/sys/vm/drop_caches so it's not a surprise that it happened. BTW, counts of *events* don't really belong in meminfo. These really do belong in /proc/vmstat if anything.