From: Minchan Kim <minchan@kernel.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: "Huang, Ying" <ying.huang@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
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, swap: Make VMA based swap readahead configurable
Date: Wed, 27 Sep 2017 14:04:01 +0900 [thread overview]
Message-ID: <20170927050401.GA715@bbox> (raw)
In-Reply-To: <20170926132129.dbtr2mof35x4j4og@dhcp22.suse.cz>
On Tue, Sep 26, 2017 at 03:21:29PM +0200, Michal Hocko wrote:
> On Thu 21-09-17 09:33:10, Huang, Ying wrote:
> > From: Huang Ying <ying.huang@intel.com>
> >
> > This patch adds a new Kconfig option VMA_SWAP_READAHEAD and wraps VMA
> > based swap readahead code inside #ifdef CONFIG_VMA_SWAP_READAHEAD/#endif.
> > This is more friendly for tiny kernels.
>
> How (much)?
>
> > And as pointed to by Minchan
> > Kim, give people who want to disable the swap readahead an opportunity
> > to notice the changes to the swap readahead algorithm and the
> > corresponding knobs.
>
> Why would anyone want that?
>
> Please note that adding new config options make the already complicated
> config space even more problematic so there should be a good reason to
> add one. Please make sure your justification is clear on why this is
> worth the future maintenance and configurability burden.
The problem is users have disabled swap readahead by echo 0 > /proc/sys/
vm/page-cluster are regressed by this new interface /sys/kernel/mm/swap/
vma_ra_max_order. Because for disabling readahead completely, they should
disable vma_ra_max_order as well as page-cluster from now on.
So, goal of new config to notice new feature to admins so they can be aware
of new konb vma_ra_max_order as well as page-cluster.
I canont think other better idea to preventing such regression.
http://lkml.kernel.org/r/%3C20170913014019.GB29422@bbox%3E
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next prev parent reply other threads:[~2017-09-27 5:04 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-21 1:33 [PATCH] mm, swap: Make VMA based swap readahead configurable Huang, Ying
2017-09-25 5:41 ` Minchan Kim
2017-09-25 5:54 ` Huang, Ying
2017-09-25 6:17 ` Minchan Kim
2017-09-25 6:24 ` Huang, Ying
2017-09-25 6:30 ` Minchan Kim
2017-09-26 13:21 ` Michal Hocko
2017-09-27 1:36 ` Huang, Ying
2017-09-27 5:04 ` Minchan Kim [this message]
2017-09-27 7:48 ` Michal Hocko
2017-09-27 8:04 ` Minchan Kim
2017-09-27 8:35 ` Michal Hocko
2017-09-27 13:15 ` Minchan Kim
2017-09-27 13:22 ` Michal Hocko
2017-09-27 13:41 ` Minchan Kim
2017-09-27 13:50 ` Michal Hocko
2017-09-27 14:10 ` Minchan Kim
2017-09-27 14:17 ` Michal Hocko
2017-09-28 1:02 ` Huang, Ying
2017-10-02 7:23 ` Michal Hocko
2017-10-02 15:45 ` Dave Hansen
2017-10-02 21:49 ` Andrew Morton
2017-10-06 12:28 ` huang ying
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