From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gorcunov@gmail.com>
Return-Path: <gorcunov@gmail.com>
Date: Mon, 13 May 2019 14:41:31 +0300
From: Cyrill Gorcunov <gorcunov@gmail.com>
Subject: Re: [RFC v2] slab_arena: Enhance slab_arena_create to support
 madvise hints
Message-ID: <20190513114131.GD2544@uranus.lan>
References: <20190506174321.11614-1-gorcunov@gmail.com>
 <20190513100642.h3ye4sphinkcemv4@esperanza>
 <20190513103032.GB2544@uranus.lan>
 <20190513112156.zqozm26fee2ddchs@esperanza>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20190513112156.zqozm26fee2ddchs@esperanza>
To: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: tml <tarantool-patches@freelists.org>, Alexander Turenko <alexander.turenko@tarantool.org>
List-ID: <tarantool-patches.dev.tarantool.org>

On Mon, May 13, 2019 at 02:21:56PM +0300, Vladimir Davydov wrote:
> On Mon, May 13, 2019 at 01:30:32PM +0300, Cyrill Gorcunov wrote:
> > > > +check_symbol_exists(MADV_NORMAL sys/mman.h TARANTOOL_SMALL_HAS_MADV_NORMAL)
> > > > +check_symbol_exists(MADV_DONTDUMP sys/mman.h TARANTOOL_SMALL_HAS_MADV_DONTDUMP)
> > > 
> > > Do we really need to check all of that? Is a check for MADV_DONTDUMP not
> > > enough?
> > 
> > Well, strictly speaking we should check each definition we use, because I'm
> > not sure if MADV_NORMAL defined on other than linux environments.
> 
> Why do we use MADV_NORMAL, anyway? We only need MADV_DONTDUMP or
> am I missing something?

Because we need a default value, which would be different
from MADV_DONTDUMP. Actually MADV_NORMAL = 0 in linux and
I think we may even live without this member initialized
but for code readability sake I assign mode to MADV_NORMAL
by default.