This commit is intended as a refinement of the patches
mentioned below, where origins/sources of newlib items
were added to the header files for user documentation.
However, if those additions are to be truly effective,
along with kernel documentation (where available), the
following prerequisites must also have been satisfied:
. our identifiers closely align with linux field names
. our derived items are documented or self-documenting
Satisfying those prerequisites prompted this patch and
for these changes, kernel sources were emphasized over
available documentation (shame on me, it should always
have been so). And, while some 'new' fields were found
to be conditional, they were included unconditionally.
These changes appear more extensive than they actually
need be since I have attempted to enforce some spacing
conventions. So, I've summarize the significant things
in the sections that follow. For a proper perspective,
use: 'git diff --ignore-space-change' (good as alias).
___________________________________________ <PIDS> api
This api is unique in that there exists many different
file/directory origins subordinate to /proc/<pid>. And
our item identifiers are sometimes coerced so as to be
able to group related or similar enumerators together.
So, users needed more help relating our identifiers to
an actual documented field. Thus, we will now also add
the field names as with 'stat: delayacct_blkio_ticks'.
Each item ending with a '_C' now consistently includes
both the parent's count/time plus waited for children.
That 'RTPRIO' guy was renamed/relocated as PRIORITY_RT
since its original name is an implementation artifact.
___________________________________________ <STAT> api
The only api change was to correct a typo ('dervied').
_________________________________________ <VMSTAT> api
Even ignoring white space, this interface received the
largest number of changes. Mostly, this was because of
deficiencies in the proc(5) documentation. Recall that
this documentation already sorely lacks any substance.
Usually, just kernel releases are noted, not contents.
When compared to kernel source, that proc(5) contained
many non-existent fields and also omitted many others.
________________________________________ <MEMINFO> api
Sadly, with this api many of the changes were simply a
correction of some earlier 'human error' where several
fields where hashed then tracked but never represented
with an item enumerator in this meminfo.h header file.
_______________________________________ <SLABINFO> api
The 'SLABS' (summary) & 'SLABNODE' items were reversed
since the former are derived from the separate caches.
More significantly, those 'SLABNODE' guys were renamed
to 'SLAB' since they concern individual caches and the
concept of 'nodes' is really an implementation detail.
Also, several enumerators were changed to more closely
agree with official slabinfo(5) documentation referred
to in what we're treating as a base document: proc(5).
Lastly, while those 'SLABS' items are solely a product
of our library and not represented in slabinfo(5), the
names attempt to parallel those found as 'SLAB' items.
______________________________________ <DISKSTATS> api
One enumeration identifier was changed so as to better
reflect its relationship to that actual documentation:
'Documentation/iostats.txt', as referenced in proc(5).
Reference(s):
. 12/2018, item origins added (and commit msg history)
commit 96d59cbf46
. 01/2019, <stat> origins tweaked
commit 201e816b26
Signed-off-by: Jim Warner <james.warner@comcast.net>
This patch just polishes the 'origin' comments for the
<STAT> header file. In particular those derived/unique
items (the 'SUM' guys) will now be properly explained.
[ in order to employ the 'derived from above' phrase ]
[ with their DELTA versions, all SUM items had to be ]
[ relocated (and some renamed). in turn, that had an ]
[ impact on many portions of the .c source file too. ]
Reference(s):
. summary calculations introduced
commit 2c86c4984a
. origins added to header files
commit 96d59cbf46
Signed-off-by: Jim Warner <james.warner@comcast.net>
A lack of documentation seems to be the major obstacle
to releasing this new library. So, in an effort to get
the ball rolling again, this patch adds the origins of
each item as a comment to six of the new header files.
However, before reviewing how such changes may benefit
that documentation objective, it seemed appropriate to
first reflect on newlib's background & current status.
___________________________________________ BACKGROUND
Discussions about and work on a new library began back
in July 2012 but quickly died. After a lull of 2 years
those discussions were resumed in August 2014 but soon
died also (and no code survived the gitorious demise).
With those early discussions, the recommended approach
was to encapsulate all of the libprocps data offerings
in individual functions. When it came to extensibility
it was suggested we should rely on symbols versioning.
Unfortunately that approach would have made for a huge
Application Programming Interface virtually impossible
to master or even document. And, runtime call overhead
would have been substantial for ps and especially top.
So, an alternative design was sought but there were no
new suggestions/contributions via freelists or gitlab.
Thus, in spite of a lack of library design experience,
the procps-ng team (Craig & Jim) set out to develop an
alternative API, more concise and with lower overhead.
Reference(s):
. 07/01/2012, begin library design discussion
https://www.freelists.org/post/procps/Old-library-calls
. 08/12/2014, revival of library design discussion
https://www.freelists.org/post/procps/libprocs-redesign
_____________________________________ DESIGN EVOLUTION
Our newlib branch first appeared on June 14, 2015. And
our current API actually represents the 4th generation
during the past 3 years of evolution. First, there was
a basic 'new', 'get' and 'unref' approach, using enums
to minimize the proliferation of 'get' function calls.
Then, in anticipation of other programs like ps, where
multiple fields times multiple processes would greatly
increase the number of 'get' function calls, a concept
of 'chains' was introduced. This became generation #2.
Such 'chains' proved unnecessarily complex so 'stacks'
replaced them. This was considered the 3rd generation,
but too many implementation details were still exposed
requiring those users to 'alloc', 'read', 'fill', etc.
Finally, a 4th generation emerged representing several
refinements to standardize and minimize those exported
functions, thus hiding all implementation details from
the users. Lastly, handling of 'errno' was normalized.
Reference(s):
. 06/14/2015, revival of new API discussion
https://www.freelists.org/post/procps/The-library-API-again
. 06/24/2015, birth of the newlib branch
https://www.freelists.org/post/procps/new-library
. 06/29/2015, 2nd generation introduced 'chains'
https://www.freelists.org/post/procps/new-library,8
. 07/22/2015, 3rd generation introduced 'stacks'
https://www.freelists.org/post/procps/newlib-stacks-vs-chains
. 06/18/2016, 4th generation refinements begin
https://www.freelists.org/post/procps/newlib-generation-35
. 11/10/2017, 4th generation standardized 'errno'
https://www.freelists.org/post/procps/some-more-master-newlib-stuff
_______________________________________ CURRENT DESIGN
Central to this new design is a simple 'result' struct
reflecting an item plus its value (thanks to a union).
As a user option, these item structures can be grouped
into 'stacks', yielding many results with just 1 call.
Such a 'stack' can be seen as a variable length record
whose content/order is determined solely by the users.
Within that 'result' structure, the union has standard
C language types so there is never a doubt how a value
should be used in a printf statement. Given that linux
requires a least a 32-bit platform the only difference
in capacity surrounds 'long' integers. And, where such
types might be used, the 32-bit maximums are adequate.
The items themselves are simply enumerators defined in
the respective header files. A user can name any items
of interest then the library magically provides result
structure(s). The approach was proven to be extensible
without breaking the ABI (in commit referenced below).
The 6 major APIs each provide for the following calls:
. 'new' ---------> always required as the first call .
. 'ref' -------------------------> strictly optional .
. 'unref' --------> optional, if ill-behaved program .
. 'get' --------------------> retrieve a single item .
. 'select' ----------------> retrieve multiple items .
And the 'get' and 'select' functions provide for delta
results representing the difference between successive
get/select calls (or a 'new' then 'get/select' call).
For the <diskstats>, <pids>, <slabinfo> & <stat> APIs,
where results are unpredictable, a 'reap' function can
return multiple result structures for multiple stacks.
The <pids> API differs from others in that those items
of interest must be provided at 'new' or 'reset' time,
a function unique to this API. And the <pids> 'select'
function requires PIDs or UIDs which are to be fetched
which then operates as a subset of 'reap'. Lastly, the
'get' function is an iterator for successive PIDs/TIDs
returning items previously identified via 'new/reset'.
To provide assistance to users during development, the
special header 'proc/xtra-procps-debug.h' is available
to check type usage against library expectations. That
check is activated by including this header explicitly
or via build using: ./configure '-DXTRA_PROCPS_DEBUG'.
Reference(s):
. 08/05/2016, type validation introduced
https://www.freelists.org/post/procps/newlib-types-validation
commit e3270d463d
. 08/11/2016, extensibility while preserving ABI example
https://www.freelists.org/post/procps/new-meminfo-fields
commit 09e1886c9e
_________________________ INITIAL DOCUMENTATION EFFORT
The initial attempt, referenced below, dealt primarily
with the <pids> interface. Separate man pages for each
exported function were created. Plus there was another
document describing the items, among other miscellany.
Adopting such an approach encounters several problems:
1. In order to use these man pages, users are required
to already know how to use the library. Or alternately
one could randomly search each of them while trying to
ascertain which function call satisfies their need and
what exactly was the proper compliment/order required.
2. While we can explain what all of those <pids> items
represent, that certainly isn't true for all the APIs.
See the gaps in kernel documentation for <meminfo> and
complete lack of documentation with that <vmstat> API.
3. Our documentation effort should take pains to avoid
unnecessary implementation details. Here's an example:
. "The pointer to info will have memory"
. "allocated and a structure created."
Alternatively, the following conveys user requirements
while not offering any internal implementation detail:
. "You must provide the address of a NULL"
. "info structure pointer."
Reference(s):
. 01/04/2017, initial documentation offering
https://www.freelists.org/post/procps/Using-reap-and-get
commit 2598e9f2ce
___________________ RECOMMENDED DOCUMENTATION APPROACH
I recommend that the newlib documentation consist of 3
man pages only. The first would cover the 5 major APIs
and their common functions. The second would deal with
the <pids> API exclusively, explaining how it differs.
Any remaining exported libproc functions which are yet
to be included could be represented in a 3rd document.
For these new documents the following are are assumed:
1. Since we will not be able to document all items, we
shouldn't try to document any items. We should instead
rely on proc(5) or Documentation/filesystems/proc.txt.
2. Program development often involves referencing some
header file(s). So, make that an absolute requirement.
3. With the addition of item origins, represented with
this commit, and considering that 'types' were already
present, the header file might be all some users need.
4. And who knows, when a user of our libproc complains
about gaps in their documentation, it might prompt the
kernel folks to correct those long standing omissions.
To summarize, I suggest that we replace that libproc.3
document with a more general one explaining the basics
of accessing this new library and the common calls for
most of the major interfaces. We can then create a new
document (libproc-pids.3?), which explains differences
in using the <PIDS> application programming interface.
A final document (libproc-misc.3?) covers what's left.
Signed-off-by: Jim Warner <james.warner@comcast.net>
If we ever were to eliminate the procps.h header file,
as discussed in the thread referenced below, then that
would impair the current XTRA_PROCPS_DEBUG provisions.
The only remaining way to verify result types would be
to explicitly include that <proc/xtra-procps-debug.h>.
So, this commit will once again enable the ./configure
provision for defining the -DXTRA_PROCPS_DEBUG option.
Reference(s):
https://www.freelists.org/post/procps/newlib-Qualys-patches,6
Signed-off-by: Jim Warner <james.warner@comcast.net>
When 'newlib' was introduced, in the commit referenced
below, the use of that glibc '__BEGIN_DECLS' macro was
standardized. However, as issue #88 revealed, this may
result in a fatal build error with other environments.
So, this patch just trades that macro for the standard
'#ifdef __cplusplus' conventions (thus avoiding use of
all those '#include <features.h>' directives as well).
Reference(s):
. newlib introduced
commit a410e236ab
. procps-ng-3.3.13 issue
https://gitlab.com/procps-ng/procps/issues/88
. some additional discussion
https://www.freelists.org/post/procps/PATCH-Replace-glibcspecific-macros-in-procnumah,1
. musl wiki (see: sys/cdefs.h error messages)
https://wiki.musl-libc.org/faq.html
Signed-off-by: Jim Warner <james.warner@comcast.net>
This commit arose out of the discussion (and research)
surrounding the issue cited below. It is an attempt to
consolidate and standardize the calculation of jiffies
categories (e.g. 'idle', 'busy', etc.) once & for all.
Also included is the enum STAT_TIC_NUM_CONTRIBUTORS in
case anyone, in the future, decides to calculate usage
based upon elapsed time * Hz (like top does in process
level %CPU stats). In such an event, a total number of
CPUs or NUMA Nodes would be needed for proper scaling.
Reference(s):
https://gitlab.com/procps-ng/procps/issues/48
Signed-off-by: Jim Warner <james.warner@comcast.net>
This commit just contains some tweaks to comments plus
a few adjustments to whitespace for alignment purposes
and a normalization of the header inclusion #define's.
[ plus a spelling error in one header file was fixed ]
Signed-off-by: Jim Warner <james.warner@comcast.net>
When users call the native 'get' functions they have a
responsibility to check that the result struct address
was indeed returned. But when using those 'GET' macros
there was no protection for possible NULL dereference.
So this patch will add some protection for a potential
failure of an underlying 'get' function. And should it
occur then those 'GET' macros will just return a zero.
Plus, we'll also mirror that behavior in the debugging
header should the XTRA_PROCPS_DEBUG #define be active.
And, we might as well add a warning when invalid items
are passed to 'GET' macros, just like we do for 'VAL'.
[ lastly, we added the missing opening parens/braces ]
[ to 2 'GET' macros in that xtra-procps-debug.h file ]
[ which went unnoticed until the qa folks caught up. ]
Signed-off-by: Jim Warner <james.warner@comcast.net>
This patch will set the stage for validating the types
referenced in the result union. For now, the parameter
representing that 'info' structure will remain unused.
[ and while we're at it, let us correct a faulty GET ]
[ macro in the diskstats header. that puppy missed a ]
[ parm which ain't so good if that guy is ever used! ]
Signed-off-by: Jim Warner <james.warner@comcast.net>
With this patch, all of the modules which offer a reap
function (pids, diskstats, slabinfo and stat too) will
now also provide for sorting whatever had been reaped.
It was easy to overlook a sort function for our <STAT>
guy given the paucity of CPUs on your typical personal
desktop or laptop. However, out in the world one might
find boxes with hundreds of CPUs plus many NUMA nodes.
Hey, who are we to disallow sorts on something another
person might see as useful under the above conditions?
And, there's always something to be said for symmetry.
[ of course, several minor tweaks were also included ]
Signed-off-by: Jim Warner <james.warner@comcast.net>
Many of our item enumerator identifiers are very long,
especially in that <VMSTAT> module. Additionally, they
all contain the exact same universal 'PROCPS_' prefix.
The origins for this are likely found in the desire to
avoid name clashes with other potential include files.
But with procps-ng newlib, we've probably gone way too
far. Did 'PROCPS_PIDS_TICS_SYSTEM' actually offer more
protection against clash than 'PIDS_TICS_SYSTEM' does?
I don't think so. Besides, no matter how big that name
becomes, one can never guarantee they'll never be some
clash. And, conversely, extremely short names will not
always create conflict. Of course, in either case when
some clash occurs, one can always #undef that problem.
Thus, this commit will eliminate that 'PROCPS_' prefix
making all of those enum identifiers a little shorter.
And, we'll still be well above some ridiculously short
(criminally short) names found in some common headers:
- - - - - - - - - - <term.h>
- 'tab', 'TTY', etc
- - - - - - - - - - - - - - - - <search.h>
- 'ENTER', ENTRY', 'FIND', etc
------------------------------------------------------
Finally, with this as a last of the wholesale changes,
we will have established the naming conventions below:
. only functions will begin with that 'procps_' prefix
. exposed structures begin with the module/header name
. item enumerators begin like structs, but capitalized
. other enumerators work exactly like item enumerators
. macros and constants begin just like the enumerators
------------------------------------------------------
Signed-off-by: Jim Warner <james.warner@comcast.net>
This patch attempts to standardize the naming of those
most important (declared not defined) context structs.
The present practice represents a hodge podge of names
only some of which reflect the source /proc file name.
And 2 of those file names embed a literal 'info' which
is likely the origin of that required parm identifier.
Now we'll append a universal '_info' to such structure
names, while including the names of those /proc pseudo
files where possible. In any case, that context struct
will *always* begin with the actual module/header file
name. And only the following two sound a little weird!
---------> 'meminfo_info' + 'slabinfo_info' <---------
Signed-off-by: Jim Warner <james.warner@comcast.net>
The following commit message is shared with 4 patches.
------------------------------------------------------
Under the newlib interface most of our 'get' functions
represent a bit of a compromise in that the actual raw
values are coerced into one (probably ok) return type.
That approach creates the possibility of truncation at
best, and wouldn't serve future needs should something
other than numeric data be added to the 'get' results.
This commit trades the current compromise for a return
value guaranteed to satisfy all future needs, namely a
pointer to a particular api's specific results struct.
The impact on existing programs is minimal, especially
when using a new supplied macro. Otherwise, native 'C'
syntax could be used, but may feel somewhat unnatural.
[ as an aside, this new approach allows us to delete ]
[ all 'getsfunc' table entries & the supporting code ]
Signed-off-by: Jim Warner <james.warner@comcast.net>
Following is a summary of significant changes (if any)
to each of these now upgraded 3rd gen library modules.
<meminfo> ............................................
. eliminated duplicate decl of 'struct procps_meminfo'
. standardized/normalized results struct union members
. added 'std' & 'var' dividers in .c file, like <pids>
. how did i miss relocating all these friggin' #undefs
. cleanup 'get' return logic (remove a redundant 'if')
<pids> ...............................................
. repositioned the procps_pidsinfo structure in header
. removed the extra trailing comma from enum pids_item
. standardized/normalized results struct union members
<slabinfo> ...........................................
. corrected comment typo (jeeze, in an 'aligned' para)
. standardized/normalized results struct union members
. added 'std' & 'var' dividers in .c file, like <pids>
. removed an obsolete #undef from procps_slabinfo_sort
. cleanup 'get' return logic (remove a redundant 'if')
<stat> ...............................................
. how did i miss relocating all these friggin' #undefs
. corrected an initialization fencepost used with numa <=== see Craig, here's a bug fix
. removed the extra trailing comma from enum stat_item
. standardized/normalized results struct union members
. added 'std' & 'var' dividers in .c file, like <pids>
. strengthen those parm checks in procps_stat_get func
. cleanup 'get' return logic (remove a redundant 'if')
<vmstat> .............................................
. standardized/normalized results struct union members
. added 'std' & 'var' dividers in .c file, like <pids>
. cleanup 'get' return logic (remove a redundant 'if')
[ virtually all of these tweaks reflect the author's ]
[ continuing pursuit of an unreasonable goal -- that ]
[ of a 'perfect' (plus 'pretty') C language program! ]
Signed-off-by: Jim Warner <james.warner@comcast.net>
With the dust now settling on all those 3rd generation
upgrades, this patch tries to provide some consistency
among the separate modules involved. Someday we should
consider a 4th generation where all redundant code has
been removed and isolated in a new shared source file.
Following is a summary of significant changes (if any)
to each of these now upgraded 3rd gen library modules.
<meminfo> ............................................
. strictly formatting/comment changes, code unaffected
<pids> ...............................................
. replaced a local mkSTR macro with existing STRINGIFY
. added fetch narrative explaining duplicate addresses
<slabinfo> ...........................................
. rearranged some free logic for procps_slabinfo_unref
. added fetch narrative explaining duplicate addresses
<stat> ...............................................
. added #define ENFORCE_LOGICAL, just as in <slabinfo>
. replaced a local mkSTR macro with existing STRINGIFY
. alphabetized the function declarations in the header
<vmstat> .............................................
. made one coverity concession with read_vmstat_failed
[ several of these changes may reflect this author's ]
[ continuing pursuit of an unreasonable goal -- that ]
[ of a 'perfect' (plus 'pretty') C language program! ]
Signed-off-by: Jim Warner <james.warner@comcast.net>
With an eye to the future, rather than managing a long
switch/case construct in the procps_stat_get function,
we'll adopt the approach used in the <meminfo> module.
By making 'get' processing table driven too, just like
'select' is already, that may ease future maintenance.
Along the way a rather large boo-boo was fixed dealing
with that /proc/stat 'procs_running' field which crept
in with the commit referenced below. It wasn't spelled
correctly and thus was never captured as PROC_RUNNING.
Reference(s):
commit abc71a46ad
Signed-off-by: Jim Warner <james.warner@comcast.net>
This commit is just my usual tweaking after an initial
submission, once the dust has settled & some more desk
checking was performed. Here are the changes included:
. get function need not check the 'stat_was_read' flag
( first time in save_sec == 0 so branch always taken )
. some table logic appeared outside the proper section
. cleanup_stack's loop made to work like assign_result
. eliminated an include of procps.h from stat.h header
. removed 'ext_numitems' from the stacks_extent struct
. changed the alignment of three prototypes for stat.h
. reorganized the pointers for 'stacks_extents' struct
. improved types indentation in header for readability
. lastly, some really gratuitous changes made to align
- comments within that private 'stacks_alloc' function
Signed-off-by: Jim Warner <james.warner@comcast.net
This commit represents a complete redesign of the stat
interface. Gone are the confusing 8 separate accessors
along with their 2 additional read functions. In their
place we have just 3 accessors, with no read required.
That old interface also suffered an inflexibility with
respect to structures. Now we deal with an unchanging
standard 'result' struct enabling future changes where
the binary interface will no longer need to be broken.
And gone is that former unnecessary typedef, used when
dealing with jiffies. Now the standard C type is used.
Our new API also adds some brand new functionality. If
a caller plans to employ successive 'select' or 'reap'
invocations, then delta values are available (which is
actually only what that top program is interested in).
At some future point a 'sort' function could be easily
introduced to complement the 'reap' function. However,
I saw no need for it at present and so it was omitted.
There were several design decisions which everyone may
not agree with. In support I'll offer these rationals:
. The 'get' function returns a signed long long result
which means a potential loss of some significance. But
I felt the ability to distinguish actual errors (minus
values) from true zero results were worth such a risk.
. The DELTA item enumerators were also made signed and
smaller than their parents. And they are intentionally
grouped as last so as to emphasize those distinctions.
. The SYS type items were excluded from the new 'reap'
function. It would not make sense to duplicate them in
each results stack. They're limited to 'get'/'select'.
. By the same token, some items (DELTA, etc.) will not
be allowed under that 'get' routine. That function was
already open to significant internal overhead (through
subsequent calls like in vmstat.c). That is why it has
been limited via 1 second between reads of /proc/stat.
Lastly, when we finally get around to documenting this
interface there's a real potential toe stubber when it
comes to the numa node portion. The libnuma.so doesn't
really provide any means to retrieve the active nodes.
Thus, any total reported by <stat> is just the highest
node number plus one, as reported by the numa library.
Any unused/inactive nodes are identified through these
. PROCPS_STAT_TIC_ID shows as PROCPS_STAT_NODE_INVALID
By the same token after the STAT_REAP_CPUS_ONLY 'reap'
. PROCPS_STAT_TIC_NUMA_NODE = PROCPS_STAT_NODE_INVALID
Reference(s):
http://www.freelists.org/post/procps/newlib-stat-interface
Signed-off-by: Jim Warner <james.warner@comcast.net>
In an attempt to normalize the 'stat' interface, we'll
first shed any reminders of the old readproc interface
by changing file names to be more descriptive & brief.
Signed-off-by: Jim Warner <james.warner@comcast.net>
