Re: [v3] hugetlbfs: Extend the definition of hugepages parameter to support node allocation
From: zhenguo yao
Date: Thu Sep 09 2021 - 06:35:24 EST
Thanks for your careful review. The processing of those parameters are
really complicated. I will fix all you mentioned soon
Mike Kravetz <mike.kravetz@xxxxxxxxxx> 于2021年9月9日周四 上午7:13写道：
>
> 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@xxxxxxxxx>
>
> 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