linux-kernel - Re: [PATCH v2] RFC: clear 1G pages with streaming stores on x86

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Message-ID: <20180725143850.GA2886@bombadil.infradead.org>
Date:   Wed, 25 Jul 2018 07:38:50 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     "Elliott, Robert (Persistent Memory)" <elliott@....com>
Cc:     Cannon Matthews <cannonmatthews@...gle.com>,
        Michal Hocko <mhocko@...nel.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andres Lagar-Cavilla <andreslc@...gle.com>,
        Salman Qazi <sqazi@...gle.com>, Paul Turner <pjt@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Peter Feiner <pfeiner@...gle.com>,
        Alain Trinh <nullptr@...gle.com>
Subject: Re: [PATCH v2] RFC: clear 1G pages with streaming stores on x86

On Wed, Jul 25, 2018 at 05:02:46AM +0000, Elliott, Robert (Persistent Memory) wrote:
> Even with that, one CPU core won't saturate the memory bus; multiple
> CPU cores (preferably on the same NUMA node as the memory) need to
> share the work.

It's probably OK to not saturate the memory bus; it'd be nice if other
cores were allowed to get work done.  If your workload is single-threaded,
you're right, of course, but who has a single-threaded workload these
days?!