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    SubjectRe: [PATCH 4/4] hugetlb: add hugepages_node= command-line option
    On Sat, 2014-02-15 at 02:06 -0800, David Rientjes wrote:
    > On Fri, 14 Feb 2014, Luiz Capitulino wrote:
    > > > Again, I think this syntax is horrendous and doesn't couple well with the
    > > > other hugepage-related kernel command line options. We already have
    > > > hugepages= and hugepagesz= which you can interleave on the command line to
    > > > get 100 2M hugepages and 10 1GB hugepages, for example.
    > > >
    > > > This patchset is simply introducing another variable to the matter: the
    > > > node that the hugepages should be allocated on. So just introduce a
    > > > hugepagesnode= parameter to couple with the others so you can do
    > > >
    > > > hugepagesz=<size> hugepagesnode=<nid> hugepages=<#>
    > >
    > > That was my first try but it turned out really bad. First, for every node
    > > you specify you need three options.
    > Just like you need two options today to specify a number of hugepages of a
    > particular non-default size. You only need to use hugepagesz= or
    > hugepagenode= if you want a non-default size or a specify a particular
    > node.
    > > So, if you want to setup memory for
    > > three nodes you'll need to specify nine options.
    > And you currently need six if you want to specify three different hugepage
    > sizes (?). But who really specifies three different hugepage sizes on the
    > command line that are needed to be reserved at boot?
    > If that's really the usecase, it seems like you want the old
    > CONFIG_PAGE_SHIFT patch.
    > > And it gets worse, because
    > > hugepagesz= and hugepages= have strict ordering (which is a mistake, IMHO) so
    > > you have to specify them in the right order otherwise things don't work as
    > > expected and you have no idea why (have been there myself).
    > >
    > How is that difficult? hugepages= is the "noun", hugepagesz= is the
    > "adjective". hugepages=100 hugepagesz=1G hugepages=4 makes perfect sense
    > to me, and I actually don't allocate hugepages on the command line, nor
    > have I looked at Documentation/kernel-parameters.txt to check if I'm
    > constructing it correctly. It just makes sense and once you learn it it's
    > just natural.

    This can get annoying _really_ fast for larger systems.

    > > IMO, hugepages_node=<nid>:<nr_pages>:<size>,... is good enough. It's concise,
    > > and don't depend on any other option to function. Also, there are lots of other
    > > kernel command-line options that require you to specify multiple fields, so
    > > it's not like hugepages_node= is totally different in that regard.
    > >


    > I doubt Andrew is going to want a completely different format for hugepage
    > allocations that want to specify a node and have to deal with people who
    > say hugepages_node=2:1:1G and constantly have to lookup if it's 2
    > hugepages on node 1 or 1 hugepage on node 2.

    I guess most users won't even be aware of this new parameter and those
    who really care will have the choice.

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      Last update: 2014-02-18 07:41    [W:9.223 / U:0.004 seconds]
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