Subject: Re: [BUG] Slow SATA disk - waiting in balance_dirty_pages() on
 i686-pae.html
To: Michal Hocko <mhocko@kernel.org>
Cc: linux-mm@kvack.org,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <2a526c85-0e27-7a5d-f606-66c74499352a@univention.de>
 <20170802122901.GB2529@dhcp22.suse.cz>
From: Philipp Hahn <hahn@univention.de>
Organization: Univention GmbH
Message-ID: <56b13e56-05c9-da59-d9a5-2a69c19e2cf4@univention.de>
Date: Wed, 2 Aug 2017 16:57:13 +0200
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Hello,

Am 02.08.2017 um 14:29 schrieb Michal Hocko:
> On Tue 01-08-17 12:32:40, Philipp Hahn wrote:
>> ;TL,DR: apt-get is blocked by balance_dirty_pages() with linux-{3,16
>> 4.2, 4.9}, but fast after reboot.
>>
>>
>> We still have several systems running 4.9.0-ucs104-686-pae. They have 16
>> GiB RAM and two disk:
> 
> I would strongly discourage you from using 32b system with so much
> memory. This will always bump into problems because of the inherent
> kernel/userspace split. Also I would bet that the problem you are seeing
> is the lack of lowmem memory which is considered for the dirty writers
> throttling unless you have vm.highmem_is_dirtyable is set to 1 which is
> not the case in your setup.

Thank you for the hint, I will give it a try.

Philipp