linux-kernel - Re: [PATCH v4 5/7] mm: rework non-root kmem

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Message-ID: <0100016abbcb13b1-a1f70846-1d8c-4212-8e74-2b9be8c32ce7-000000@email.amazonses.com>
Date:   Wed, 15 May 2019 14:00:09 +0000
From:   Christopher Lameter <cl@...ux.com>
To:     Roman Gushchin <guro@...com>
cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Shakeel Butt <shakeelb@...gle.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, kernel-team@...com,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Rik van Riel <riel@...riel.com>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        cgroups@...r.kernel.org
Subject: Re: [PATCH v4 5/7] mm: rework non-root kmem_cache lifecycle
 management

On Tue, 14 May 2019, Roman Gushchin wrote:

> To make this possible we need to introduce a new percpu refcounter
> for non-root kmem_caches. The counter is initialized to the percpu
> mode, and is switched to atomic mode after deactivation, so we never
> shutdown an active cache. The counter is bumped for every charged page
> and also for every running allocation. So the kmem_cache can't
> be released unless all allocations complete.

Increase refcounts during each allocation? Looks to be quite heavy
processing.