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Message-ID: <d445cda6-873b-5be5-cda1-1f886bce700c@oracle.com>
Date: Wed, 8 Sep 2021 16:13:21 -0700
From: Mike Kravetz <mike.kravetz@...cle.com>
To: yaozhenguo <yaozhenguo1@...il.com>
Cc: corbet@....net, akpm@...ux-foundation.org, yaozhenguo@...com,
willy@...radead.org, linux-kernel@...r.kernel.org,
linux-doc@...r.kernel.org,
Linux Memory Management List <linux-mm@...ck.org>
Subject: Re: [v3] hugetlbfs: Extend the definition of hugepages parameter to
support node allocation
On 9/1/21 11:59 PM, yaozhenguo 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 hugepages in one node. For example: DPDK needs hugepages
> which is in the same node as NIC. if DPDK needs four hugepages of 1G
> size in node1 and system has 16 numa nodes. We must reserve 64 hugepages
> in kernel cmdline. But, only four hugepages are used. The others should
> be free after boot.If the system memory is low(for example: 64G), it will
^ add space after . please
> be an impossible task. So, extend hugepages kernel parameter to specify
> node number of hugepages to allocate at boot.
> For example add following parameter:
>
> hugepagesz=1G hugepages=0:1,1:3
>
> It will allocate 1 hugepages in node0 and 3 hugepages in node1.
>
> Signed-off-by: yaozhenguo <yaozhenguo1@...il.com>
Thank you for continuing to work this! This kernel command line parsing
code is tricky, and there is still something missing in your changes.
I also added some suggestions to change working of documentation.
> ---
> v3: 1. Skip gigantic hugepages allocation if hugetlb_cma is enabled.
> 2. Fix wrong behavior for parameter: hugepagesz=2M hugepages=2 hugepages=5.
> 3. Update hugetlbpage.rst.
> 4. Fix side effects which v2 brings in.
> 5. add cond_resched in hugetlb_hstate_alloc_pages_onenode.
> ---
> .../admin-guide/kernel-parameters.txt | 8 +-
> Documentation/admin-guide/mm/hugetlbpage.rst | 12 +-
> include/linux/hugetlb.h | 1 +
> mm/hugetlb.c | 116 ++++++++++++++++--
> 4 files changed, 126 insertions(+), 11 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index bdb22006f..64a128924 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1588,9 +1588,11 @@
> the number of pages of hugepagesz to be allocated.
> If this is the first HugeTLB parameter on the command
> line, it specifies the number of pages to allocate for
> - the default huge page size. See also
> - Documentation/admin-guide/mm/hugetlbpage.rst.
> - Format: <integer>
> + the default huge page size. If using node format, It
> + specifies numbers of hugepage in a specific node.
Perhaps rewrite as?
the default huge page size. If using node format, the
number of pages to allocate per-node can be specified.
> + See also Documentation/admin-guide/mm/hugetlbpage.rst.
> + Format: <integer> or (node format)
> + <node>:<numbers>[,<node>:<numbers>]
Perhaps node format should be written as?
<node>:<integer>[,<node>:<integer>]
>
> hugepagesz=
> [HW] The size of the HugeTLB pages. This is used in
> diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation/admin-guide/mm/hugetlbpage.rst
> index 8abaeb144..bc5f674ff 100644
> --- a/Documentation/admin-guide/mm/hugetlbpage.rst
> +++ b/Documentation/admin-guide/mm/hugetlbpage.rst
> @@ -128,7 +128,9 @@ hugepages
> implicitly specifies the number of huge pages of default size to
> allocate. If the number of huge pages of default size is implicitly
> specified, it can not be overwritten by a hugepagesz,hugepages
> - parameter pair for the default size.
> + parameter pair for the default size. This parameter also has node
> + format. It specifies numbers of hugepage in a specific node when
> + using node format.
Perhaps rewrite as?
parameter pair for the default size. This parameter also has a
node format. The node format specifies the number of huge pages
to allocate on specific nodes.
>
> For example, on an architecture with 2M default huge page size::
>
> @@ -138,6 +140,14 @@ hugepages
> indicating that the hugepages=512 parameter is ignored. If a hugepages
> parameter is preceded by an invalid hugepagesz parameter, it will
> be ignored.
> +
> + Node format example::
> +
> + hugepagesz=2M hugepages=0:1,1:2
> +
> + It will allocate 1 2M hugepages in node0 and 2 2M hugepages in node1.
> + If the node number exceeds the maximum node, the parameter will be
> + ignored.
Perhaps rewrite as?
It will allocate 1 2M hugepage on node0 and 2 2M hugepages on node1.
If the node number is invalid, the parameter will be ignored.
> default_hugepagesz
> Specify the default huge page size. This parameter can
> only be specified once on the command line. default_hugepagesz can
<snip>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
<snip>
> @@ -3580,6 +3641,10 @@ static int __init hugetlb_init(void)
> default_hstate_max_huge_pages;
> }
> }
> + for (i = 0; i < nodes_weight(node_states[N_MEMORY]); i++)
> + if (default_hugepages_in_node[i] > 0)
> + default_hstate.max_huge_pages_node[i] =
> + default_hugepages_in_node[i];
Logic like the above for loop also needs to be added to the routine
default_hugepagesz_setup. See the code block starting with:
if (default_hstate_max_huge_pages) {
The kernel command line parameters,
hugepages=0:1,1:3 default_hugepagesz=1G
should allocate 1 1G page on node 0 and 3 1G pages on node 1. With this
patch it will allocate 2 1G pages on node 0 and 2 1G pages on node 1.
--
Mike Kravetz
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