linux-kernel - Re: [PATCH] mm/swap: add function get_total_swap_pages to expose total_swap

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Message-ID: <5ac13913-783d-26aa-ea5f-ab375f450f4c@amd.com>
Date:   Tue, 30 Jan 2018 13:52:16 +0100
From:   Christian König <christian.koenig@....com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     "He, Roger" <Hongbo.He@....com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH] mm/swap: add function get_total_swap_pages to expose
 total_swap_pages

Am 30.01.2018 um 13:28 schrieb Michal Hocko:
> I do think you should completely ignore the size of the swap space. IMHO
> you should forbid further allocations when your current buffer storage
> cannot be reclaimed. So you need some form of feedback mechanism that
> would tell you: "Your buffers have grown too much".

Yeah well, that is exactly what we are trying to do here.

> If you cannot do
> that then simply assume that you cannot swap at all rather than rely on
> having some portion of it for yourself. There are many other users of
> memory outside of your subsystem. Any scaling based on the 50% of resource
> belonging to me is simply broken.

Our intention is not reserve 50% of resources to TTM, but rather allow 
TTM to abort when more than 50% of all resources are used up.

Rogers initial implementation didn't looked like that, but that is just 
a minor mistake we can fix.

Regards,
Christian.