From: Michal Hocko <mhocko@kernel.org>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>,
Souptick Joarder <jrdr.linux@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
shaoyafang@didiglobal.com
Subject: Re: [PATCH] mm: compaction: some tracepoints should be defined only when CONFIG_COMPACTION is set
Date: Tue, 12 Mar 2019 17:44:22 +0100 [thread overview]
Message-ID: <20190312164422.GD5721@dhcp22.suse.cz> (raw)
In-Reply-To: <CALOAHbBR119mzbkkQ5fmGQ5Bqxu2O4EFgq89gVRXqXN+USzDEA@mail.gmail.com>
On Wed 13-03-19 00:29:57, Yafang Shao wrote:
> On Wed, Mar 13, 2019 at 12:18 AM Michal Hocko <mhocko@kernel.org> wrote:
> >
> > On Sat 02-03-19 12:38:58, Yafang Shao wrote:
> > > Only mm_compaction_isolate_{free, migrate}pages may be used when
> > > CONFIG_COMPACTION is not set.
> > > All others are used only when CONFIG_COMPACTION is set.
> >
> > Why is this an improvement?
> >
>
> After this change, if CONFIG_COMPACTION is not set, the tracepoints
> that only work when CONFIG_COMPACTION is set will not be exposed to
> the usespace.
> Without this change, they will always be expose in debugfs no matter
> CONFIG_COMPACTION is set or not.
And this is exactly something that the changelog should mention. I
wasn't aware that we do export tracepoints even when they are not used
by any code path. This whole macro based programming is just a black
magic.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-03-12 16:44 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-02 4:38 [PATCH] mm: compaction: show gfp flag names in try_to_compact_pages tracepoint Yafang Shao
2019-03-02 4:38 ` [PATCH] mm: compaction: some tracepoints should be defined only when CONFIG_COMPACTION is set Yafang Shao
2019-03-12 16:18 ` Michal Hocko
2019-03-12 16:29 ` Yafang Shao
2019-03-12 16:44 ` Michal Hocko [this message]
2019-03-12 16:48 ` Yafang Shao
2019-03-02 23:04 ` [PATCH] mm: compaction: show gfp flag names in try_to_compact_pages tracepoint kbuild test robot
2019-03-04 2:25 ` Yafang Shao
2019-03-12 16:17 ` Michal Hocko
2019-03-14 8:30 ` Vlastimil Babka
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