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Date:   Wed, 3 Mar 2021 14:26:12 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Christoph Lameter <cl@gentwo.de>
Cc:     Xunlei Pang <xlpang@linux.alibaba.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Wen Yang <wenyang@linux.alibaba.com>,
        Roman Gushchin <guro@fb.com>, Pekka Enberg <penberg@gmail.com>,
        Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
        David Rientjes <rientjes@google.com>,
        linux-kernel@vger.kernel.org,
        "linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH v2 3/3] mm/slub: Use percpu partial free counter
Message-ID: <20210303142612.GC2723601@casper.infradead.org>
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 <alpine.DEB.2.22.394.2103021012010.860725@gentwo.de>
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On Tue, Mar 02, 2021 at 10:14:53AM +0100, Christoph Lameter wrote:
> On Mon, 10 Aug 2020, Xunlei Pang wrote:
> > -	atomic_long_t partial_free_objs;
> > +	atomic_long_t __percpu *partial_free_objs;
> 
> A percpu counter is never atomic. Just use unsigned long and use this_cpu
> operations for this thing. That should cut down further on the overhead.

What about allocations from interrupt context?  Should this be a local_t
instead?