linux-kernel - Re: [PATCH v2] memblock: Add flags and nid info in memblock debugfs

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Message-ID: <CALJQGLnNohj8w_Cd-wX40eNoWVUCsRePHV0QvkTP9L7wJvU+Eg@mail.gmail.com>
Date:   Thu, 18 May 2023 13:58:46 +0800
From:   Yuwei Guan <ssawgyw@...il.com>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        akpm@...ux-foundation.org, tsahu@...ux.ibm.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] memblock: Add flags and nid info in memblock debugfs

Mike Rapoport <rppt@...nel.org> 于2023年5月17日周三 21:42写道：
>
> On Wed, May 17, 2023 at 11:37:25AM +0530, Anshuman Khandual wrote:
> >
> > On 5/17/23 08:27, Yuwei Guan wrote:
> > > Currently, the memblock debugfs can display the count of memblock_type and
> > > the base and end of the reg. However, when the following scenario occurs,
> >
> > scenarios where the memblock flags or nid varies inside a single PA range ?
> > I guess the commit message description here can be improved to accommodate
> > such details.
> >
> > > the information in the existing debugfs cannot make it clear why the
> > > address is not consecutive.
> > >
> > > For example,
> > > cat /sys/kernel/debug/memblock/memory
> > >    0: 0x0000000080000000..0x00000000901fffff
> > >    1: 0x0000000090200000..0x00000000905fffff
> > >    2: 0x0000000090600000..0x0000000092ffffff
> > >    3: 0x0000000093000000..0x00000000973fffff
> > >    4: 0x0000000097400000..0x00000000b71fffff
> > >    5: 0x00000000c0000000..0x00000000dfffffff
> > >    6: 0x00000000e2500000..0x00000000f87fffff
> > >    7: 0x00000000f8800000..0x00000000fa7fffff
> > >    8: 0x00000000fa800000..0x00000000fd3effff
> > >    9: 0x00000000fd3f0000..0x00000000fd3fefff
> > >   10: 0x00000000fd3ff000..0x00000000fd7fffff
> > >   11: 0x00000000fd800000..0x00000000fd901fff
> > >   12: 0x00000000fd902000..0x00000000fd909fff
> > >   13: 0x00000000fd90a000..0x00000000fd90bfff
> > >   14: 0x00000000fd90c000..0x00000000ffffffff
> > >   15: 0x0000000880000000..0x0000000affffffff
> > >
> > > So we can add flags and nid to this debugfs.
> > >
> > > For example,
> > > cat /sys/kernel/debug/memblock/memory
> > > cnt     base..end       flags   nid
> >
> > These markers ^^^ are not aligned properly, and also might not be
> > required as well.
> >
> > > 0:      0x0000000080000000..0x00000000901fffff  0x0     0x0
> > > 1:      0x0000000090200000..0x00000000905fffff  0x4     0x0
> > > 2:      0x0000000090600000..0x0000000092ffffff  0x0     0x0
> > > 3:      0x0000000093000000..0x00000000973fffff  0x4     0x0
> > > 4:      0x0000000097400000..0x00000000b71fffff  0x0     0x0
> > > 5:      0x00000000c0000000..0x00000000dfffffff  0x0     0x0
> > > 6:      0x00000000e2500000..0x00000000f87fffff  0x0     0x0
> > > 7:      0x00000000f8800000..0x00000000fa7fffff  0x4     0x0
> > > 8:      0x00000000fa800000..0x00000000fd3effff  0x0     0x0
> > > 9:      0x00000000fd3f0000..0x00000000fd3fefff  0x4     0x0
> > > 10:     0x00000000fd3ff000..0x00000000fd7fffff  0x0     0x0
> > > 11:     0x00000000fd800000..0x00000000fd901fff  0x4     0x0
> > > 12:     0x00000000fd902000..0x00000000fd909fff  0x0     0x0
> > > 13:     0x00000000fd90a000..0x00000000fd90bfff  0x4     0x0
> > > 14:     0x00000000fd90c000..0x00000000ffffffff  0x0     0x0
> > > 15:     0x0000000880000000..0x0000000affffffff  0x0     0x0
> > >
> > > Signed-off-by: Yuwei Guan <ssawgyw@...il.com>
> > > Reviewed-by: Tarun Sahu <tsahu@...ux.ibm.com>
> > > ---
> > >  mm/memblock.c | 8 ++++++--
> > >  1 file changed, 6 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/mm/memblock.c b/mm/memblock.c
> > > index 511d4783dcf1..b36fb6b31e0f 100644
> > > --- a/mm/memblock.c
> > > +++ b/mm/memblock.c
> > > @@ -2144,12 +2144,16 @@ static int memblock_debug_show(struct seq_file *m, void *private)
> > >     int i;
> > >     phys_addr_t end;
> > >
> > > +   seq_puts(m, "cnt\tbase..end\tflags\tnid\n");
> >
> > Please drop this.
> >
> > > +
> > >     for (i = 0; i < type->cnt; i++) {
> > >             reg = &type->regions[i];
> > >             end = reg->base + reg->size - 1;
> > >
> > > -           seq_printf(m, "%4d: ", i);
> > > -           seq_printf(m, "%pa..%pa\n", &reg->base, &end);
> > > +           seq_printf(m, "%d:\t", i);
> >
> > Why drop the existing %4d formatting qualifier ?
> >
> > > +           seq_printf(m, "%pa..%pa\t", &reg->base, &end);
> > > +           seq_printf(m, "0x%x\t", reg->flags);
> >
> > Should there be ORed string values for each memblock flag ?
> >
> > enum memblock_flags {
> >         MEMBLOCK_NONE           = 0x0,  /* No special request */
> >         MEMBLOCK_HOTPLUG        = 0x1,  /* hotpluggable region */
> >         MEMBLOCK_MIRROR         = 0x2,  /* mirrored region */
> >         MEMBLOCK_NOMAP          = 0x4,  /* don't add to kernel direct mapping */
> >         MEMBLOCK_DRIVER_MANAGED = 0x8,  /* always detected via a driver */
> > };
> >
> > Something like NN | HT | MR | NM | DM ?
>
> These are not less cryptic than numbers :)
> Most of them are mutually exclusive, so maybe just spell them out fully,
> just shorten DRIVER_MANAGED to DRV_MNG?
> And make the flags dump the last to keep columns nicely aligned.
>

Ok, I will update them in the v3 patch soon.

Thanks
> > > +           seq_printf(m, "0x%x\n", memblock_get_region_node(reg));
> > >     }
> > >     return 0;
> > >  }
>
> --
> Sincerely yours,
> Mike.