Re: [PATCH] Laptop-mode v7 for linux 2.6.1

From: Jens Axboe <axboe@suse.de>
To: Jan De Luyck <lkml@kcore.org>
Cc: Kiko Piris <kernel@pirispons.net>, Bart Samwel <bart@samwel.tk>,
	linux-kernel@vger.kernel.org, Dax Kelson <dax@gurulabs.com>,
	Bartek Kania <mrbk@gnarf.org>,
	Simon Mackinlay <smackinlay@mail.com>
Subject: Re: [PATCH] Laptop-mode v7 for linux 2.6.1
Date: Mon, 12 Jan 2004 15:02:38 +0100	[thread overview]
Message-ID: <20040112140238.GG24638@suse.de> (raw)
In-Reply-To: <200401121409.44187.lkml@kcore.org>

On Mon, Jan 12 2004, Jan De Luyck wrote:
> On Monday 12 January 2004 13:19, Kiko Piris wrote:
> > On 12/01/2004 at 12:12, Jan De Luyck wrote:
> > > Patch applied, kernel built, laptop_mode activated, but my disk just
> > > doesn't want to spin down...
> >
> > [...]
> >
> > > But the disk never spins down. Not that I can tell, hdparm -C /dev/hda
> > > always tells me active/idle, and the sdsl tool also reports 100% disk
> > > spinning...
> > >
> > > anything else I have to activate/check?
> >
> > As you don't say if you have checked it, here goes my suggestion:
> >
> > First of all, you should assure there's no process doing reads [*] that
> > cause a cache miss (eg. daemons like postfix that check the queue every
> > few seconds). You can tell this running vmstat 1 and see that bi and bo
> > [**] stay at 0.
> 
> vmstat 1:
> 
>  0  0      0  88748  37628 216216    0    0     0     0 1514  1130  7  4 89  0
>  0  0      0  88756  37628 216216    0    0     0     0 1495  1123  6  1 93  0
>  0  0      0  88748  37628 216216    0    0     0     0 1504  1114  8  4 88  0
>  1  0      0  88748  37628 216216    0    0     0     0 1499  1058  6  2 92  0
>  0  0      0  88748  37628 216216    0    0     0     0 1488  1062  7  4 89  0
>  0  0      0  88748  37628 216216    0    0     0     0 1480  1007  7  6 87  0
>  0  0      0  88876  37628 216216    0    0     0     0 1524  1122  7  6 87  0
>  0  0      0  88748  37628 216216    0    0     0     0 1506  1078 11  6 83  0
>  0  0      0  88748  37628 216216    0    0     0     0 1500  1057 11  5 84  0
>  0  0      0  88748  37628 216216    0    0     0     0 1514  1040 16  3 81  0
>  0  1      0  88748  37660 216216    0    0     0    28 1523  1041 19  4 64 13
>  0  1      0  88748  37660 216216    0    0     0     0 1500   994 23  2  0 75
>  0  0      0  88748  37660 216216    0    0     0    32 1540  1064 25  1 53 21
>  0  0      0  88748  37660 216216    0    0     0     0 1501  1064 24  0 76  0
>  0  0      0  88748  37660 216216    0    0     0     0 1514  1071 24  1 75  0
>  2  0      0  88812  37660 216216    0    0     0     0 1518  1086 24  1 75  0
>  0  0      0  88804  37660 216216    0    0     0     0 1504  1066 24  2 74  0
>  0  0      0  88740  37660 216216    0    0     0     0 1482  1015 25  1 74  0
> 
> At the presence of bo it spins up the disk.

bo is accounted when io is actually put on the pending queue for the
disk, so they really do go hand in hand. So you should use block_dump to
find out why.

-- 
Jens Axboe