From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 94CECC433E0 for ; Tue, 26 Jan 2021 10:42:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4ED21230FD for ; Tue, 26 Jan 2021 10:42:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404227AbhAZKml (ORCPT ); Tue, 26 Jan 2021 05:42:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53914 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731742AbhAZCE5 (ORCPT ); Mon, 25 Jan 2021 21:04:57 -0500 Received: from mail-qk1-x72f.google.com (mail-qk1-x72f.google.com [IPv6:2607:f8b0:4864:20::72f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 388D9C0611C2 for ; Mon, 25 Jan 2021 16:53:36 -0800 (PST) Received: by mail-qk1-x72f.google.com with SMTP id g19so551070qki.2 for ; Mon, 25 Jan 2021 16:53:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=BcKx8yKk9DEzeYQ1umTI+yLBl6nPj9ta1OpCtTjEqbQ=; b=njnDopwPY7IHJTT3bdBrU9QfFha4FxpxvTw/x0eCbFDHDRkNCsMhN+UQ8bqUqh+nhI arbXAHIod5UjilnecY3GMdwiG9CkFv/AoitTOC0pGdAMapHEH+1EXa9PS06XyY+iwklW 3xZR+MdCR4jnI8L57SQhpX2x5w6gqYroe06iSaPQuj6Zv7YSMlxhKJZeq0b+wgBw3kT9 8MqiisibVyyyv7yJkXZhmWOE8+Fa6EyKnp+86TU1Hfw+W+QNIEe6Jds13qc0wx6tx/KX GJzaD5UUS1yjmPg5fEPwLQ4S2gjz2NUKBaHgQTfYwffboht2+lJqDU4R62maGsAvJbRp OVPg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=BcKx8yKk9DEzeYQ1umTI+yLBl6nPj9ta1OpCtTjEqbQ=; b=bCudxR8pMZLAobyNnx+s/P3hh4hHLHWD0sjA3AXZN3qiUF1qA8PzVVEFU0xltdfyUx BUK9HrmPdx1hX1L6UJB+HHx87/a7yl7j48q9W19LS+WCyKd3LUAkoMI21d7mHLtVdmA4 HhqIw9sj0MLMLpSN+Ht5DPmxmUixFF94AJt+LCCISAgD7kVp4B57hOb0giy+UN3a548y 8hNFn/KFWwgl3oGSf3T+UHKA7J7eKfChg86Qzq2k6Qdrh3jj8ARKFKfv5Hu7CtXiUKrL MiafB+LxocSxLA6lsByw6ngdVjI9hIZnVfxeWfmhI2ANDVGqYkQdW/tkihJR2Tq0pyWp nnPg== X-Gm-Message-State: AOAM530kbCz+pIIeFEfkBBPe2rdCBvJ2MOOCLQ0T6wKqsezdQpFharIu f388GiDV9p0EVFtbWmfaG70= X-Google-Smtp-Source: ABdhPJzNSrqw8AGfWL6w4wY3IRVZzKaALDklw4GZn0asaDzWVB/jdpCgw+2C2dmFj2yeGLIXJSZj+w== X-Received: by 2002:a37:a909:: with SMTP id s9mr3577509qke.489.1611622415327; Mon, 25 Jan 2021 16:53:35 -0800 (PST) Received: from localhost (dhcp-6c-ae-f6-dc-d8-61.cpe.echoes.net. [72.28.8.195]) by smtp.gmail.com with ESMTPSA id i18sm13174644qkg.66.2021.01.25.16.53.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Jan 2021 16:53:34 -0800 (PST) Sender: Tejun Heo Date: Mon, 25 Jan 2021 19:53:35 -0500 From: Tejun Heo To: Dave Hansen 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 Subject: Re: [PATCH] x86/mm: Tracking linear mapping split events since boot Message-ID: References: <30752f8e-16e9-d093-e6ec-31fd45715e9d@intel.com> <0d402da9-d7a2-a3b4-eb6f-bd1b768b3a85@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0d402da9-d7a2-a3b4-eb6f-bd1b768b3a85@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Dave. On Mon, Jan 25, 2021 at 04:47:42PM -0800, Dave Hansen wrote: > The patch here does not actually separate out pre-boot from post-boot, > so it's pretty hard to tell if the splits came from something like > tracing which is totally unnecessary or they were the result of > something at boot that we can't do anything about. Ah, right, didn't know they also included splits during boot. It'd be a lot more useful if they were counting post-boot splits. > 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. Thanks. -- tejun