linux-kernel - Re: [PATCH] hugetlbfs: add hugepages

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Message-ID: <YSLPWybBCyE/6x7s@casper.infradead.org>
Date:   Sun, 22 Aug 2021 23:27:39 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     yaozhenguo <yaozhenguo1@...il.com>, mike.kravetz@...cle.com,
        corbet@....net, yaozhenguo@...com, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH] hugetlbfs: add hugepages_node kernel parameter

On Sun, Aug 22, 2021 at 03:19:52PM -0700, Andrew Morton wrote:
> On Fri, 20 Aug 2021 11:05:36 +0800 yaozhenguo <yaozhenguo1@...il.com> wrote:
> 
> > We can specify the number of hugepages to allocate at boot. But the
> > hugepages is balanced in all nodes at present. In some scenarios,
> > we only need hugepags in one node. For example: DPDK needs hugepages
> > which is in the same node as NIC. if DPDK needs four hugepags of 1G
> > size in node1 and system has 16 numa nodes. We must reserve 64 hugepags
> > in kernel cmdline. But, only four hugepages is used. The others should
> > be free after boot.If the system memory is low(for example: 64G), it will
> > be an impossible task. So, add hugepages_node kernel parameter to specify
> > node number of hugepages to allocate at boot.
> > For example add following parameter:
> > 
> > hugepagesz=1G hugepages_node=1 hugepages=4
> > 
> > It will allocate 4 hugepags in node1 at boot.
> 
> If were going to do this, shouldn't we permit more than one node?
> 
> 	hugepages_nodes=1,2,5

I'd think we'd be better off expanding the definition of hugepages.
eg:

hugepagesz=1G hugepages=1:4,3:8,5:2

would say to allocate 4 pages from node 1, 8 pages from node 3 and 2
pages from node 5.