Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Fri, 27 Jul 2018 12:01:22 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     Daniel Drake <drake@endlessm.com>
Cc:     mhocko@kernel.org, hannes@cmpxchg.org, linux-mm@kvack.org,
        linux@endlessm.com, linux-kernel@vger.kernel.org
Subject: Re: Making direct reclaim fail when thrashing
Message-ID: <20180727190122.GA3825@bombadil.infradead.org>
References: <20180727162143.26466-1-drake@endlessm.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20180727162143.26466-1-drake@endlessm.com>
User-Agent: Mutt/1.9.2 (2017-12-15)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, Jul 27, 2018 at 11:21:43AM -0500, Daniel Drake wrote:
> Here I'm experimenting by adding another tag to the page cache radix tree,
> tagging pages that were activated in the refault path.

NAK.  No more tags or you blow up the memory consumption of the radix
tree by 15%.

> And then in get_scan_count I'm checking how many active pages have that
> tag, and also looking at the size of the active and inactive lists.

You'd be better off using a bit in struct page somewhere ...