ps: Add PSS and USS fields

The library added smaps_rollup fields in the referenced commit.
This commit exploits the new fields to give pss and uss options.

These options were first proposed back in 2015 by Petr Malat
and, with the library update, they are finally made it into ps.

Why use proportional or unique segment size? It is argued that
these give a better idea of the "real" memory usage of a process.

References:
 commit 12543b6c76
 issue #112
 https://www.freelists.org/post/procps/PSS-and-USS-support-for-ps
 https://lwn.net/Articles/230975/

Signed-off-by: Craig Small <csmall@dropbear.xyz>

NEWS

@@ -7,6 +7,7 @@ procps-ng-NEXT
   * pkill: Check for lt- variants of program name          issue #192
   * ps: Add OOM and OOMADJ fields                          issue #198
   * ps: Add IO Accounting fields                           issue #184
+  * ps: Add PSS and USS fields                             issue #112
   * slabtop: Don't combine d and o options                 issue #160
   * top: exploit some library smaps_rollup provisions      issue #112
 

ps/common.h

@@ -144,6 +144,9 @@ makEXT(SIGCATCH)
 makEXT(SIGIGNORE)
 makEXT(SIGNALS)
 makEXT(SIGPENDING)
+makEXT(SMAP_PRV_CLEAN)
+makEXT(SMAP_PRV_DIRTY)
+makEXT(SMAP_PSS)
 makEXT(STATE)
 makEXT(SUPGIDS)
 makEXT(SUPGROUPS)

ps/global.c

@@ -131,6 +131,9 @@ makREL(SIGCATCH)
 makREL(SIGIGNORE)
 makREL(SIGNALS)
 makREL(SIGPENDING)
+makREL(SMAP_PRV_CLEAN)
+makREL(SMAP_PRV_DIRTY)
+makREL(SMAP_PSS)
 makREL(STATE)
 makREL(SUPGIDS)
 makREL(SUPGROUPS)

ps/output.c

@@ -1009,6 +1009,11 @@ setREL1(PROCESSOR)
   return snprintf(outbuf, COLWID, "%d", rSv(PROCESSOR, u_int, pp));
 }
 
+static int pr_pss(char *restrict const outbuf, const proc_t *restrict const pp){
+setREL1(SMAP_PSS)
+  return snprintf(outbuf, COLWID, "%lu", rSv(SMAP_PSS, ul_int, pp));
+}
+
 static int pr_numa(char *restrict const outbuf, const proc_t *restrict const pp){
 setREL1(PROCESSOR_NODE)
   return snprintf(outbuf, COLWID, "%d", rSv(PROCESSOR_NODE, s_int, pp));
@@ -1117,6 +1122,12 @@ setREL1(SIGCATCH)
   return help_pr_sig(outbuf, rSv(SIGCATCH, str, pp));
 }
 
+static int pr_uss(char *restrict const outbuf, const proc_t *restrict const pp){
+setREL2(SMAP_PRV_CLEAN, SMAP_PRV_DIRTY)
+  return snprintf(outbuf, COLWID, "%lu",
+	  rSv(SMAP_PRV_CLEAN, ul_int, pp) + rSv(SMAP_PRV_DIRTY, ul_int, pp));
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 /*
@@ -1707,6 +1718,7 @@ static const format_struct format_array[] = { /*
 {"projid",    "PROJID",  pr_nop,           PIDS_noop,                5,    SUN,  PO|RIGHT},
 {"pset",      "PSET",    pr_nop,           PIDS_noop,                4,    DEC,  TO|RIGHT},
 {"psr",       "PSR",     pr_psr,           PIDS_PROCESSOR,           3,    DEC,  TO|RIGHT},
+{"pss",       "PSS",     pr_pss,           PIDS_SMAP_PSS,            5,    XXX,  PO|RIGHT},
 {"psxpri",    "PPR",     pr_nop,           PIDS_noop,                3,    DEC,  TO|RIGHT},
 {"rbytes",    "RBYTES",  pr_rbytes,        PIDS_IO_READ_BYTES,       5,    LNX,  TO|RIGHT},
 {"rchars",    "RCHARS",  pr_rchars,        PIDS_IO_READ_CHARS,       5,    LNX,  TO|RIGHT},
@@ -1802,6 +1814,7 @@ static const format_struct format_array[] = { /*
 {"userns",    "USERNS",  pr_userns,        PIDS_NS_USER,            10,    LNX,  ET|RIGHT},
 {"usertime",  "USER",    pr_nop,           PIDS_noop,                4,    DEC,  ET|RIGHT},
 {"usrpri",    "UPR",     pr_nop,           PIDS_noop,                3,    DEC,  TO|RIGHT}, /*upr*/
+{"uss",       "USS",     pr_uss,           PIDS_SMAP_PRV_CLEAN,      5,    XXX,  PO|RIGHT},
 {"util",      "C",       pr_c,             PIDS_extra,               2,    SGI,  ET|RIGHT}, // not sure about "C"
 {"utime",     "UTIME",   pr_nop,           PIDS_TICS_USER,           6,    LNx,  ET|RIGHT},
 {"utsns",     "UTSNS",   pr_utsns,         PIDS_NS_UTS,             10,    LNX,  ET|RIGHT},

ps/ps.1

@@ -4,7 +4,7 @@
 .\" Quick hack conversion by Albert Cahalan, 1998.
 .\" Licensed under version 2 of the Gnu General Public License.
 .\"
-.TH PS "1" "2021-03-29" "procps-ng" "User Commands"
+.TH PS "1" "2021-06-16" "procps-ng" "User Commands"
 .\"
 .\" To render this page:
 .\"    groff -t -b -man -X -P-resolution -P100 -Tps ps.1 &
@@ -1524,6 +1524,11 @@ psr	PSR	T{
 processor that process last executed on.
 T}
 
+pss	PSS	T{
+Proportional share size, the non-swapped physical memory, with shared memory
+proportionally accounted to all tasks mapping it.
+T}
+
 rbytes	RBYTES	T{
 Number of bytes which this process really did cause to be fetched from the storage layer.
 T}
@@ -1855,6 +1860,11 @@ See
 .IR namespaces (7).
 T}
 
+uss	USS	T{
+Unique set size, the non-swapped physical memory, which
+is not shared with an another task.
+T}
+
 utsns	UTSNS	T{
 Unique inode number describing the namespace the process belongs to.
 See