From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot1-x344.google.com (mail-ot1-x344.google.com [IPv6:2607:f8b0:4864:20::344]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 383272115993B for ; Thu, 27 Sep 2018 08:33:42 -0700 (PDT) Received: by mail-ot1-x344.google.com with SMTP id c12-v6so2964870otl.6 for ; Thu, 27 Sep 2018 08:33:42 -0700 (PDT) MIME-Version: 1.0 References: <153802226065.833068.11943510429252969385.stgit@dwillia2-desk3.amr.corp.intel.com> <20180927071135.GB6959@linux-x5ow.site> In-Reply-To: <20180927071135.GB6959@linux-x5ow.site> From: Dan Williams Date: Thu, 27 Sep 2018 08:33:30 -0700 Message-ID: Subject: Re: [PATCH 0/3] acpi, nfit: Add dirty shutdown count to sysfs List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Johannes Thumshirn Cc: Linux ACPI , linux-nvdimm List-ID: On Thu, Sep 27, 2018 at 12:12 AM Johannes Thumshirn wrote: > > On Wed, Sep 26, 2018 at 09:24:20PM -0700, Dan Williams wrote: > > The Intel NVDIMM command specification publishes a dirty-shutdown-count > > in addition to the dirty-shutdown / flush-failed indication that comes > > from the ACPI NFIT. This is expected to be a common property of NVDIMMs > > and is a static hardware health detail to be cached / exported via > > sysfs. > > > > Add plumbing for retrieving this data at driver load time, publish the > > count, and use the dynamically retrieved dirty-shutdown indicator to > > augment the existing 'flush_failed' flag. > > Is this the same thing as the LSS Latch stuff that went into ndctl? It's a replacement. The latch mechanism is awkward especially when all that it needed is a rolling count of dirty-shutdown events. The expectation going forward is that the platform firmware will handle the latch, if it is present, and the OS need only consume the dirty-shutdown count. The ndctl implementation called libndctl apis from the udev queue which we discovered injects unnecessary udev queue drains / stalls into the boot path. Lastly, the userspace caching scheme for non-root users to consume the dirty-shutdown-count just isn't as efficient as teaching the kernel to cache this value and export it as a standard sysfs attribute. _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm