From: Michal Hocko <mhocko@suse.cz>
To: Mark Hills <mark@xwax.org>
Cc: Vlastimil Babka <vbabka@suse.cz>,
linux-mm@kvack.org, Mel Gorman <mgorman@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: Write throughput impaired by touching dirty_ratio
Date: Wed, 24 Jun 2015 11:16:50 +0200 [thread overview]
Message-ID: <20150624091650.GC32756@dhcp22.suse.cz> (raw)
In-Reply-To: <558A69F8.2080304@suse.cz>
On Wed 24-06-15 10:27:36, Vlastimil Babka wrote:
> [add some CC's]
>
> On 06/19/2015 05:16 PM, Mark Hills wrote:
[...]
> > The system is an HP xw6600, running i686 kernel. This happens whether
How many CPUs does the machine have?
> > internal SATA HDD, SSD or external USB drive is used. I first saw this on
> > kernel 4.0.4, and 4.0.5 is also affected.
OK so this is 32b kernel which might be the most important part. What is
the value of /proc/sys/vm/highmem_is_dirtyable? Also how does your low
mem vs higmem look when you are setting the ratio (cat /proc/zoneinfo)?
It seems Vlastimil is right and a bogus ratelimit_pages is calculated
and your writers are throttled every few pages.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2015-06-24 9:16 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-19 15:16 Mark Hills
2015-06-24 8:27 ` Vlastimil Babka
2015-06-24 9:16 ` Michal Hocko [this message]
2015-06-24 22:26 ` Mark Hills
2015-06-25 9:20 ` Michal Hocko
2015-06-25 12:56 ` Michal Hocko
2015-06-25 21:45 ` Mark Hills
2015-07-01 15:40 ` Michal Hocko
2015-06-25 9:30 ` Vlastimil Babka
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