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Message-ID: <55D78FB0.9040906@redhat.com>
Date: Fri, 21 Aug 2015 16:53:04 -0400
From: Rik van Riel <riel@...hat.com>
To: Xishi Qiu <qiuxishi@...wei.com>,
LKML <linux-kernel@...r.kernel.org>,
Linux MM <linux-mm@...ck.org>
CC: Xiexiuqi <xiexiuqi@...wei.com>
Subject: Re: is this a problem of numactl in RedHat7.0 ?
On 08/21/2015 05:27 AM, Xishi Qiu wrote:
> I use numactl(--localalloc) tool run a test case, but it shows that
> the numa policy is prefer, I don't know why.
The kernel implements MPOL_PREFERRED and MPOL_LOCAL
in the same way. Look at this code in mpol_new(),
in mm/mempolicy.c:
/*
* MPOL_PREFERRED cannot be used with MPOL_F_STATIC_NODES or
* MPOL_F_RELATIVE_NODES if the nodemask is empty (local
allocation).
* All other modes require a valid pointer to a non-empty nodemask.
*/
if (mode == MPOL_PREFERRED) {
if (nodes_empty(*nodes)) {
if (((flags & MPOL_F_STATIC_NODES) ||
(flags & MPOL_F_RELATIVE_NODES)))
return ERR_PTR(-EINVAL);
}
} else if (mode == MPOL_LOCAL) {
if (!nodes_empty(*nodes))
return ERR_PTR(-EINVAL);
mode = MPOL_PREFERRED;
} else if (nodes_empty(*nodes))
return ERR_PTR(-EINVAL);
--
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