[dpdk-dev] [RFC 9/9] usertools/lib: add GRUB utility library for hugepage config

[Kevin Wilson]

Hi, Anatoly,

Thanks for these patches, good work.
Regarding "update-grub": IIRC, this is Ubuntu specific command (and
also used in Debian/Debian based flavors).
In Fedora (RedHat based) recent distros, you use grub2-mkconfig
instead (and there is no "update-grub", IIRC).
If this is true, I would consider adding a comment in the commit log
saying something like "it is for Ubuntu/Debian-based distros".
So maybe in the future someone will add the python code which detects
the OS (using lsb-release, etc) and, in case it is Fedora/RedHat
distro, the grub2-mkconfig util
will be invoked instead.
Regards,
KW


On Mon, Jun 25, 2018 at 6:59 PM, Anatoly Burakov
<anatoly.burakov at intel.com> wrote:
> This library is highly experimental and can kill kittens, but its
> main purpose is to automatically set up GRUB command-line to
> allocate a given number of hugepages at boot time. It works in
> a similar way HugeUtil library does, but instead of committing
> changes to fstab or runtime configuration, it commits its
> changes to GRUB default command-line and updates all GRUB entries
> afterwards. I got it to a state where it's safe to use on my
> system, but see the part above about killing kittens - you have
> been warned :)
>
> No example scripts will currently be provided.
>
> Signed-off-by: Anatoly Burakov <anatoly.burakov at intel.com>
> ---
>  usertools/DPDKConfigLib/GrubHugeUtil.py | 175 ++++++++++++++++++++++++
>  1 file changed, 175 insertions(+)
>  create mode 100755 usertools/DPDKConfigLib/GrubHugeUtil.py
>
> diff --git a/usertools/DPDKConfigLib/GrubHugeUtil.py b/usertools/DPDKConfigLib/GrubHugeUtil.py
> new file mode 100755
> index 000000000..4b8e349b8
> --- /dev/null
> +++ b/usertools/DPDKConfigLib/GrubHugeUtil.py
> @@ -0,0 +1,175 @@
> +#!/usr/bin/env python
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright(c) 2018 Intel Corporation
> +
> +
> +from .PlatformInfo import *
> +from .Util import *
> +import re
> +import os
> +
> +__KERNEL_TRANSPARENT_HP = "/sys/kernel/mm/transparent_hugepage/enabled"
> +_GRUB_CMDLINE_PARAM_NAME = "GRUB_CMDLINE_LINUX_DEFAULT"
> +
> +# local copy of platform info
> +info = PlatformInfo()
> +
> +def _find_linux_default_cmdline():
> +    with open("/etc/default/grub") as f:
> +        for line in f:
> +            line = line.strip()
> +            if line.startswith(_GRUB_CMDLINE_PARAM_NAME):
> +                return line
> +        else:
> +            raise RuntimeError("Invalid GRUB default configuration format")
> +
> +
> +def _parse_linux_default_cmdline(line):
> +    # get value to the right of equals sign, strip whitespace and quotes,
> +    # split into separate keys and make a list of values
> +    _, cmdline = kv_split(line, "=")
> +    # remove quotes
> +    if cmdline[0] == cmdline[-1] == '"':
> +        cmdline = cmdline[1:-1]
> +
> +    return [kv_split(v, "=") for v in cmdline.split()]
> +
> +
> +def _generate_linux_default_cmdline(cmdline):
> +    lines = []
> +    cmdline_idx = -1
> +    with open("/etc/default/grub") as f:
> +        for idx, line in enumerate(f):
> +            line = line.strip()
> +            lines.extend([line])
> +            if line.startswith(_GRUB_CMDLINE_PARAM_NAME):
> +                cmdline_idx = idx
> +        if cmdline_idx == -1:
> +            raise RuntimeError("Invalid GRUB default configuration format")
> +
> +    # write the lines back, replacing one we want
> +    with open("/etc/default/grub", "w") as f:
> +        for idx, line in enumerate(lines):
> +            if idx == cmdline_idx:
> +                line = cmdline
> +            f.write(line + "\n")
> +
> +
> +def _find_transparent_hugepage():
> +    if not os.path.exists(__KERNEL_TRANSPARENT_HP):
> +        return None
> +    value = read_file(__KERNEL_TRANSPARENT_HP)
> +    m = re.search(r"\[([a-z]+)\]", value)
> +    if not m:
> +        raise RuntimeError("BUG: Bad regular expression")
> +    return m.group(1)
> +
> +
> +class GrubHugepageConfig:
> +    def __init__(self):
> +        self.update()
> +
> +    def update(self):
> +        self.reset()
> +
> +        hugepage_sizes = info.hugepage_sizes_supported
> +        if len(hugepage_sizes) == 0:
> +            raise RuntimeError("Hugepages appear to be unsupported")
> +        cmdline = _find_linux_default_cmdline()
> +        values = _parse_linux_default_cmdline(cmdline)
> +
> +        # parse values in the list
> +        self.default_hugepagesz = info.default_hugepage_size
> +        self.transparent_hugepage = _find_transparent_hugepage()
> +        sizes = []
> +        nrs = []
> +        for k, v in values:
> +            if k == "default_hugepagesz":
> +                self.default_hugepagesz = human_readable_to_kilobytes(v)
> +            elif k == "transparent_hugepage":
> +                self.transparent_hugepage = v
> +            elif k == "hugepagesz":
> +                sizes.append(human_readable_to_kilobytes(v))
> +            elif k == "hugepages":
> +                nrs.append(v)
> +        if len(sizes) != len(nrs):
> +            raise RuntimeError("GRUB hugepage configuration is wrong")
> +        detected_hugepages = dict(zip(sizes, map(int, nrs)))
> +        self.nr_hugepages = {size: detected_hugepages.get(size, 0)
> +                             for size in hugepage_sizes}
> +
> +    def commit(self):
> +        # perform sanity checks - we can't afford invalid data making it into
> +        # bootloader config, as that might render user's machine unbootable, so
> +        # tread really really carefully
> +
> +        # first, check if user didn't add any unexpected hugepage sizes
> +        configured_sizes = set(self.nr_hugepages.keys())
> +        supported_sizes = set(info.hugepage_sizes_supported)
> +
> +        if configured_sizes != supported_sizes:
> +            diff = configured_sizes.difference(supported_sizes)
> +            raise ValueError("Unsupported hugepage sizes: %s" %
> +                             [kilobytes_to_human_readable(s) for s in diff])
> +
> +        # check if default hugepage is one of the supported ones
> +        if self.default_hugepagesz is not None and\
> +                self.default_hugepagesz not in configured_sizes:
> +            s = kilobytes_to_human_readable(self.default_hugepagesz)
> +            raise ValueError("Unsupported default hugepage size: %i" % s)
> +
> +        # transparent hugepages support was added in recent kernels, so check
> +        # if user is trying to set this
> +        if _find_transparent_hugepage() is None and \
> +                        self.transparent_hugepage is not None:
> +            raise ValueError("Transparent hugepages are not unsupported")
> +
> +        # OK, parameters look to be valid - let's roll
> +
> +        # read and parse current cmdline
> +        cmdline = _find_linux_default_cmdline()
> +
> +        values = _parse_linux_default_cmdline(cmdline)
> +
> +        # clear out old data
> +        klist = ["transparent_hugepage", "default_hugepagesz",
> +                 "hugepage", "hugepagesz"]
> +        # iterate over a copy so that we could delete items
> +        for k, v in values[:]:
> +            if k in klist:
> +                values.remove((k, v))
> +
> +        # generate new cmdline
> +        cmdline = " ".join([("%s=%s" % (k, v)) if v is not None else k
> +                            for k, v in values])
> +
> +        # now, populate cmdline with new data
> +        new_items = []
> +        for sz, nr in self.nr_hugepages.items():
> +            sz = kilobytes_to_human_readable(sz)
> +            new_items += "hugepagesz=%s hugepages=%i" % (sz, nr)
> +        if self.default_hugepagesz is not None:
> +            new_items += "default_hugepagesz=%i" % self.default_hugepagesz
> +        if self.transparent_hugepage is not None:
> +            new_items += "transparent_hugepage=%s" % self.transparent_hugepage
> +
> +        cmdline = "%s %s" % (cmdline, " ".join(new_items))
> +
> +        # strip any extraneous whitespace we may have added
> +        cmdline = re.sub(r"\s\s+", " ", cmdline).strip()
> +
> +        # now, put everything back together
> +        cmdline = '%s="%s"' % (_GRUB_CMDLINE_PARAM_NAME, cmdline)
> +
> +        # write it to config
> +        _generate_linux_default_cmdline(cmdline)
> +
> +        # finally, update GRUB
> +        if not run(["update-grub"]):
> +            raise RuntimeError("Failed to update GRUB")
> +        self.update()
> +
> +    def reset(self):
> +        self.nr_hugepages = {}  # pagesz: number
> +        self.default_hugepagesz = None
> +        self.transparent_hugepage = None
> --
> 2.17.1