From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1756685AbcBWBx3 (ORCPT <rfc822;w@1wt.eu>);
	Mon, 22 Feb 2016 20:53:29 -0500
Received: from gum.cmpxchg.org ([85.214.110.215]:59610 "EHLO gum.cmpxchg.org"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1754424AbcBWBx2 (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Mon, 22 Feb 2016 20:53:28 -0500
Date: Mon, 22 Feb 2016 17:53:18 -0800
From: Johannes Weiner <hannes@cmpxchg.org>
To: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Mel Gorman <mgorman@suse.de>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH v2] mm: scale kswapd watermarks in proportion to memory
Message-ID: <20160223015318.GA30924@cmpxchg.org>
References: <1456184002-15729-1-git-send-email-hannes@cmpxchg.org>
 <1456191393.7716.28.camel@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1456191393.7716.28.camel@redhat.com>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Mon, Feb 22, 2016 at 08:36:33PM -0500, Rik van Riel wrote:
> On Mon, 2016-02-22 at 15:33 -0800, Johannes Weiner wrote:
> 
> > Beyond 1G of memory, this will produce bigger watermark steps than 
> 
> Is that supposed to be beyond 16GB?

The old formula formula is

  min = sqrt(kb * 16)
  low = min >> 2

and the new one is

  low = kb * 0.001

and

  sqrt(x/1024 * 16) >> 2 = x/1024 * 0.001

puts x at

  x = 1 << 30

Did I miss something?

> Acked-by: Rik van Riel <riel@redhat.com>

Thanks!