linux-kernel - Re: [PATCH 0/3] remove rw_page() from brd, pmem and btt

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Message-Id: <20170728142123.729b20e9fcf45c6a814f18e7@linux-foundation.org>
Date:   Fri, 28 Jul 2017 14:21:23 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Ross Zwisler <ross.zwisler@...ux.intel.com>,
        linux-kernel@...r.kernel.org, "karam . lee" <karam.lee@....com>,
        Minchan Kim <minchan@...nel.org>,
        Jerome Marchand <jmarchan@...hat.com>,
        Nitin Gupta <ngupta@...are.org>, seungho1.park@....com,
        Christoph Hellwig <hch@....de>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Chinner <david@...morbit.com>, Jan Kara <jack@...e.cz>,
        Jens Axboe <axboe@...nel.dk>,
        Vishal Verma <vishal.l.verma@...el.com>,
        linux-nvdimm@...ts.01.org
Subject: Re: [PATCH 0/3] remove rw_page() from brd, pmem and btt

On Fri, 28 Jul 2017 10:31:43 -0700 Matthew Wilcox <willy@...radead.org> wrote:

> On Fri, Jul 28, 2017 at 10:56:01AM -0600, Ross Zwisler wrote:
> > Dan Williams and Christoph Hellwig have recently expressed doubt about
> > whether the rw_page() interface made sense for synchronous memory drivers
> > [1][2].  It's unclear whether this interface has any performance benefit
> > for these drivers, but as we continue to fix bugs it is clear that it does
> > have a maintenance burden.  This series removes the rw_page()
> > implementations in brd, pmem and btt to relieve this burden.
> 
> Why don't you measure whether it has performance benefits?  I don't
> understand why zram would see performance benefits and not other drivers.
> If it's going to be removed, then the whole interface should be removed,
> not just have the implementations removed from some drivers.

Yes please.  Minchan, could you please take a look sometime?