Re: [PATCH v2 1/6] Documentation: filesystems: proc: update meminfo section

From: Johannes Weiner
Date: Wed May 11 2022 - 14:51:36 EST

On Wed, May 11, 2022 at 07:11:06PM +0200, David Hildenbrand wrote:
> On 10.05.22 17:28, Johannes Weiner wrote:
> > Add new entries. Minor corrections and cleanups.
> >
> > Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> > ---
> > Documentation/filesystems/proc.rst | 155 ++++++++++++++++++-----------
> > 1 file changed, 99 insertions(+), 56 deletions(-)
> >
> > diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
> > index 061744c436d9..736ed384750c 100644
> > --- a/Documentation/filesystems/proc.rst
> > +++ b/Documentation/filesystems/proc.rst
> > @@ -942,56 +942,71 @@ can be substantial. In many cases there are other means to find out
> > additional memory using subsystem specific interfaces, for instance
> > /proc/net/sockstat for TCP memory allocations.
> >
> > -The following is from a 16GB PIII, which has highmem enabled.
> > -You may not have all of these fields.
> > +Example output. You may not have all of these fields.
> >
> > ::
> >
> > > cat /proc/meminfo
> >
> > - MemTotal: 16344972 kB
> > - MemFree: 13634064 kB
> > - MemAvailable: 14836172 kB
> > - Buffers: 3656 kB
> > - Cached: 1195708 kB
> > - SwapCached: 0 kB
> > - Active: 891636 kB
> > - Inactive: 1077224 kB
> > - HighTotal: 15597528 kB
> > - HighFree: 13629632 kB
> > - LowTotal: 747444 kB
> > - LowFree: 4432 kB
> > - SwapTotal: 0 kB
> > - SwapFree: 0 kB
> > - Dirty: 968 kB
> > - Writeback: 0 kB
> > - AnonPages: 861800 kB
> > - Mapped: 280372 kB
> > - Shmem: 644 kB
> > - KReclaimable: 168048 kB
> > - Slab: 284364 kB
> > - SReclaimable: 159856 kB
> > - SUnreclaim: 124508 kB
> > - PageTables: 24448 kB
> > - NFS_Unstable: 0 kB
> > - Bounce: 0 kB
> > - WritebackTmp: 0 kB
> > - CommitLimit: 7669796 kB
> > - Committed_AS: 100056 kB
> > - VmallocTotal: 112216 kB
> > - VmallocUsed: 428 kB
> > - VmallocChunk: 111088 kB
> > - Percpu: 62080 kB
> > - HardwareCorrupted: 0 kB
> > - AnonHugePages: 49152 kB
> > - ShmemHugePages: 0 kB
> > - ShmemPmdMapped: 0 kB
> > + MemTotal: 32858820 kB
> > + MemFree: 21001236 kB
> > + MemAvailable: 27214312 kB
> > + Buffers: 581092 kB
> > + Cached: 5587612 kB
> > + SwapCached: 0 kB
> > + Active: 3237152 kB
> > + Inactive: 7586256 kB
> > + Active(anon): 94064 kB
> > + Inactive(anon): 4570616 kB
> > + Active(file): 3143088 kB
> > + Inactive(file): 3015640 kB
> > + Unevictable: 0 kB
> > + Mlocked: 0 kB
> > + SwapTotal: 0 kB
> > + SwapFree: 0 kB
> > + Dirty: 12 kB
> > + Writeback: 0 kB
> > + AnonPages: 4654780 kB
> > + Mapped: 266244 kB
> > + Shmem: 9976 kB
> > + KReclaimable: 517708 kB
> > + Slab: 660044 kB
> > + SReclaimable: 517708 kB
> > + SUnreclaim: 142336 kB
> > + KernelStack: 11168 kB
> > + PageTables: 20540 kB
> > + NFS_Unstable: 0 kB
> > + Bounce: 0 kB
> > + WritebackTmp: 0 kB
> > + CommitLimit: 16429408 kB
> > + Committed_AS: 7715148 kB
> > + VmallocTotal: 34359738367 kB
> > + VmallocUsed: 40444 kB
> > + VmallocChunk: 0 kB
> > + Percpu: 29312 kB
> > + HardwareCorrupted: 0 kB
> > + AnonHugePages: 4149248 kB
> > + ShmemHugePages: 0 kB
> > + ShmemPmdMapped: 0 kB
> > + FileHugePages: 0 kB
> > + FilePmdMapped: 0 kB
> > + CmaTotal: 0 kB
> > + CmaFree: 0 kB
> > + HugePages_Total: 0
> > + HugePages_Free: 0
> > + HugePages_Rsvd: 0
> > + HugePages_Surp: 0
> > + Hugepagesize: 2048 kB
> > + Hugetlb: 0 kB
> > + DirectMap4k: 401152 kB
> > + DirectMap2M: 10008576 kB
> > + DirectMap1G: 24117248 kB
> >
> > MemTotal
> > Total usable RAM (i.e. physical RAM minus a few reserved
> > bits and the kernel binary code)
> > MemFree
> > - The sum of LowFree+HighFree
> > + Total free RAM. On highmem systems, the sum of LowFree+HighFree
> > MemAvailable
> > An estimate of how much memory is available for starting new
> > applications, without swapping. Calculated from MemFree,
> > @@ -1005,8 +1020,9 @@ Buffers
> > Relatively temporary storage for raw disk blocks
> > shouldn't get tremendously large (20MB or so)
> > Cached
> > - in-memory cache for files read from the disk (the
> > - pagecache). Doesn't include SwapCached
> > + In-memory cache for files read from the disk (the
> > + pagecache) as well as tmpfs & shmem.
> > + Doesn't include SwapCached.
> > SwapCached
> > Memory that once was swapped out, is swapped back in but
> > still also is in the swapfile (if memory is needed it
> > @@ -1018,6 +1034,11 @@ Active
> > Inactive
> > Memory which has been less recently used. It is more
> > eligible to be reclaimed for other purposes
> > +Unevictable
> > + Memory that cannot be reclaimed, such as mlocked pages,
> > + ramfs backing pages, secret memfd pages etc.
>
>
> A little imprecise, because this only includes memory to be mapped into
> user space. For example, all kernel allocations are unevictable but not
> accounted here.

True. How about the below?

> Apart from that
>
> Acked-by: David Hildenbrand <david@xxxxxxxxxx>

Thanks!

Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---

diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index 9749ff8c0ecf..5e9791457876 100644
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst
@@ -1035,8 +1035,8 @@ Inactive
Memory which has been less recently used. It is more
eligible to be reclaimed for other purposes
Unevictable
- Memory that cannot be reclaimed, such as mlocked pages,
- ramfs backing pages, secret memfd pages etc.
+ Memory allocated for userspace which cannot be reclaimed, such
+ as mlocked pages, ramfs backing pages, secret memfd pages etc.
Mlocked
Memory locked with mlock().
HighTotal, HighFree