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Date:      Sat, 5 Apr 2014 01:02:08 +0400
From:      Dmitry Sivachenko <trtrmitya@gmail.com>
To:        John Baldwin <jhb@FreeBSD.org>
Cc:        freebsd-hackers@freebsd.org, =?utf-8?Q?Trond_Endrest=C3=B8l?= <Trond.Endrestol@fagskolen.gjovik.no>
Subject:   Re: madvise() vs posix_fadvise()
Message-ID:  <5426E303-E35B-4D4A-AB62-3571228A5A2C@gmail.com>
In-Reply-To: <201404041612.35889.jhb@freebsd.org>
References:  <D6BD48AF-9522-495D-8D54-37854E53C272@gmail.com> <201404031102.38598.jhb@freebsd.org> <EF134BCA-1E92-4C98-8763-9A31EA96839A@gmail.com> <201404041612.35889.jhb@freebsd.org>

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On 05 =D0=B0=D0=BF=D1=80. 2014 =D0=B3., at 0:12, John Baldwin =
<jhb@FreeBSD.org> wrote:

>=20
> MADV_WILLNEED is not going to give you what you want.  OTOH, if you =
haven't
> tried FreeBSD 10 yet, I would suggest trying that.  There have been =
changes
> to pagedaemon that might make it do a better job of kicking out the =
pages
> of the log files automatically.
>=20


I did. My situation became worse after I moved from stable/9 to =
stable/10.
My feeling is that stable/10 pushes rarely used mmaped pages out of RAM =
more aggressively than stable/9 did.

For now, the only solution I found is doing msync(MS_INVALIDATE) on log =
files after gzipping and after backup via rsync.
This moves corresponding memory pages from Inactive to Free and prevents =
system to occupy all free memory with cached log files and to purge =
mmaped data out of RAM to accomodate more disk cache.

What I would love to see is an ability to tell OS not to release mmaped =
data unless "really needed" (disk cache is not an excuse).=



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