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Date: Wed, 29 Jun 2022 08:27:03 -0700
From: Christoph Hellwig <hch@infradead.org>
To: "Dennis.Wu" <dennis.wu@intel.com>
Cc: nvdimm@lists.linux.dev, dan.j.williams@intel.com,
	vishal.l.verma@intel.com, dave.jiang@intel.com, ira.weiny@intel.com
Subject: Re: [PATCH] ACPI/NFIT: Add no_deepflush param to dynamic control
 flush operation
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References: <20220629083118.8737-1-dennis.wu@intel.com>
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On Wed, Jun 29, 2022 at 04:31:18PM +0800, Dennis.Wu wrote:
> reason: in the current BTT implimentation deepflush is always
> used and deepflush is very expensive. Since customer already
> know the ADR can protect the WPQ data in memory controller and
> no need to call deepflush to get better performance. BTT w/o
> deepflush, performance can improve 300%~600% with diff FIO jobs.
> 
> How: Add one param "no_deepflush" in the nfit module parameter.
> if "modprob nfit no_deepflush=1", customer can get the higher
> performance but not strict data security. Before modprob nfit,
> you may need to "ndctl disable-region".

This goes back to my question from years ago:  why do we ever
do this deep flush in the Linux nvdimm stack to start with?