From: Zlatko Calusic <zlatko.calusic@iskon.hr>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>, Hugh Dickins <hughd@google.com>,
Minchan Kim <minchan.kim@gmail.com>,
linux-mm <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: wait for congestion to clear on all zones
Date: Wed, 09 Jan 2013 23:52:47 +0100 [thread overview]
Message-ID: <50EDF4BF.7000108@iskon.hr> (raw)
In-Reply-To: <20130109134816.db51a820.akpm@linux-foundation.org>
On 09.01.2013 22:48, Andrew Morton wrote:
> On Wed, 09 Jan 2013 22:41:48 +0100
> Zlatko Calusic <zlatko.calusic@iskon.hr> wrote:
>
>> Currently we take a short nap (HZ/10) and wait for congestion to clear
>> before taking another pass with lower priority in balance_pgdat(). But
>> we do that only for the highest zone that we encounter is unbalanced
>> and congested.
>>
>> This patch changes that to wait on all congested zones in a single
>> pass in the hope that it will save us some scanning that way. Also we
>> take a nap as soon as congested zone is encountered and sc.priority <
>> DEF_PRIORITY - 2 (aka kswapd in trouble).
>>
>> ...
>>
>> The patch is against the mm tree. Make sure that
>> mm-avoid-calling-pgdat_balanced-needlessly.patch is applied first (not
>> yet in the mmotm tree). Tested on half a dozen systems with different
>> workloads for the last few days, working really well!
>
> But what are the user-observable effcets of this change? Less kernel
> CPU consumption, presumably? Did you quantify it?
>
And I forgot to answer all the questions... :(
Actually, I did record kswapd CPU usage after 5 days of uptime and I
intend to compare it with the new data (after few more days pass). I
expect maybe slightly better results.
But, I think it's obvious from my first reply that my primary goal with
this patch is correctness, not optimization. So, I won't be dissapointed
a little bit if kswapd CPU usage stays the same, so long as the memory
utilization remains this smooth. ;)
--
Zlatko
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next prev parent reply other threads:[~2013-01-09 22:52 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-09 21:41 Zlatko Calusic
2013-01-09 21:48 ` Andrew Morton
2013-01-09 22:15 ` Zlatko Calusic
2013-01-09 22:52 ` Zlatko Calusic [this message]
2013-01-11 1:25 ` Simon Jeons
2013-01-11 11:25 ` Zlatko Calusic
2013-01-13 0:46 ` Simon Jeons
2013-01-14 14:37 ` Zlatko Calusic
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