From: Andrew Morton <akpm@linux-foundation.org>
To: Minchan Kim <minchan@kernel.org>
Cc: "Huang, Ying" <ying.huang@intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Johannes Weiner <hannes@cmpxchg.org>,
Rik van Riel <riel@redhat.com>, Shaohua Li <shli@kernel.org>,
Hugh Dickins <hughd@google.com>,
Fengguang Wu <fengguang.wu@intel.com>,
Tim Chen <tim.c.chen@intel.com>,
Dave Hansen <dave.hansen@intel.com>
Subject: Re: [PATCH -mm -v4 3/5] mm, swap: VMA based swap readahead
Date: Thu, 14 Sep 2017 14:21:40 -0700 [thread overview]
Message-ID: <20170914142140.9c5e3ef37e6bad1d68899e64@linux-foundation.org> (raw)
In-Reply-To: <20170914131446.GA12850@bgram>
On Thu, 14 Sep 2017 22:14:46 +0900 Minchan Kim <minchan@kernel.org> wrote:
> > Now. Users can choose between VMA based readahead and original
> > readahead via a knob as follow at runtime,
> >
> > /sys/kernel/mm/swap/vma_ra_enabled
>
> It's not a config option and is enabled by default. IOW, it's under the radar
> so current users cannot notice it. That's why we want to emit big fat warnning.
> when old user set 0 to page-cluster. However, as Andrew said, it's lame.
>
> If we make it config option, product maker/kernel upgrade user can have
> a chance to notice and read description so they could be aware of two weird
> knobs and help to solve the problem in advance without printk_once warn.
> If user has no interest about swap-readahead or skip the new config option
> by mistake, it works physcial readahead which means no regression.
Yup, a Kconfig option sounds like a good idea. And that's a bit more
friendly to tiny kernels as well.
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next prev parent reply other threads:[~2017-09-14 21:21 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-07 5:40 [PATCH -mm -v4 0/5] " Huang, Ying
2017-08-07 5:40 ` [PATCH -mm -v4 1/5] mm, swap: Add swap readahead hit statistics Huang, Ying
2017-08-09 21:50 ` Andrew Morton
2017-08-09 23:17 ` Huang, Ying
2017-08-07 5:40 ` [PATCH -mm -v4 2/5] mm, swap: Fix swap readahead marking Huang, Ying
2017-08-07 5:40 ` [PATCH -mm -v4 3/5] mm, swap: VMA based swap readahead Huang, Ying
2017-09-13 1:40 ` Minchan Kim
2017-09-13 21:02 ` Andrew Morton
2017-09-14 0:53 ` Huang, Ying
2017-09-14 8:15 ` Minchan Kim
2017-09-14 7:53 ` Minchan Kim
2017-09-14 12:01 ` Huang, Ying
2017-09-14 13:14 ` Minchan Kim
2017-09-14 21:21 ` Andrew Morton [this message]
2017-09-15 3:15 ` Huang, Ying
2017-09-15 3:42 ` Minchan Kim
2017-09-15 4:46 ` Huang, Ying
2017-08-07 5:40 ` [PATCH -mm -v4 4/5] mm, swap: Add sysfs interface for " Huang, Ying
2017-08-07 5:40 ` [PATCH -mm -v4 5/5] mm, swap: Don't use VMA based swap readahead if HDD is used as swap Huang, Ying
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