Add columns for process autogroup identifier and nice value

Adds AGRP (autogroup) and ANI (autogroup nice) columns that
report the information from /proc/PID/autogroup, as well as
handlers for '{' and '}' to change the autogroup nice value.

This is guarded by /proc/sys/kernel/sched_autogroup_enabled
such that sampling and/or changing values wont be attempted
unless the kernel feature is enabled.

Fixes: #720

6 files changed, 129 insertions, 2 deletions

diff --git a/linux/LinuxProcess.c b/linux/LinuxProcess.c
index fe8492df..c353f8a7 100644
--- a/linux/LinuxProcess.c
+++ b/linux/LinuxProcess.c
@@ -100,6 +100,8 @@ const ProcessFieldData Process_fields[LAST_PROCESSFIELD] = {
    [PROC_COMM] = { .name = "COMM", .title = "COMM            ", .description = "comm string of the process from /proc/[pid]/comm", .flags = 0, },
    [PROC_EXE] = { .name = "EXE", .title = "EXE             ", .description = "Basename of exe of the process from /proc/[pid]/exe", .flags = 0, },
    [CWD] = { .name = "CWD", .title = "CWD                       ", .description = "The current working directory of the process", .flags = PROCESS_FLAG_CWD, },
+   [AUTOGROUP_ID] = { .name = "AUTOGROUP_ID", .title = "AGRP", .description = "The autogroup identifier of the process", .flags = PROCESS_FLAG_LINUX_AUTOGROUP, },
+   [AUTOGROUP_NICE] = { .name = "AUTOGROUP_NICE", .title = " ANI", .description = "Nice value (the higher the value, the more other processes take priority) associated with the process autogroup", .flags = PROCESS_FLAG_LINUX_AUTOGROUP, },
 };
 
 Process* LinuxProcess_new(const Settings* settings) {
@@ -159,6 +161,37 @@ bool LinuxProcess_setIOPriority(Process* this, Arg ioprio) {
    return (LinuxProcess_updateIOPriority((LinuxProcess*)this) == ioprio.i);
 }
 
+bool LinuxProcess_isAutogroupEnabled(void) {
+   char buf[16];
+   if (xReadfile(PROCDIR "/sys/kernel/sched_autogroup_enabled", buf, sizeof(buf)) < 0)
+      return false;
+   return buf[0] == '1';
+}
+
+bool LinuxProcess_changeAutogroupPriorityBy(Process* this, Arg delta) {
+   char buffer[256];
+   xSnprintf(buffer, sizeof(buffer), PROCDIR "/%d/autogroup", this->pid);
+
+   FILE* file = fopen(buffer, "r+");
+   if (!file)
+      return false;
+
+   long int identity;
+   int nice;
+   int ok = fscanf(file, "/autogroup-%ld nice %d", &identity, &nice);
+   bool success;
+   if (ok == 2) {
+      rewind(file);
+      xSnprintf(buffer, sizeof(buffer), "%d", nice + delta.i);
+      success = fputs(buffer, file) > 0;
+   } else {
+      success = false;
+   }
+
+   fclose(file);
+   return success;
+}
+
 #ifdef HAVE_DELAYACCT
 static void LinuxProcess_printDelay(float delay_percent, char* buffer, int n) {
    if (isnan(delay_percent)) {
@@ -259,6 +292,25 @@ static void LinuxProcess_writeField(const Process* this, RichString* str, Proces
       xSnprintf(buffer, n, "%5lu ", lp->ctxt_diff);
       break;
    case SECATTR: snprintf(buffer, n, "%-30s   ", lp->secattr ? lp->secattr : "?"); break;
+   case AUTOGROUP_ID:
+      if (lp->autogroup_id != -1) {
+         xSnprintf(buffer, n, "%4ld ", lp->autogroup_id);
+      } else {
+         attr = CRT_colors[PROCESS_SHADOW];
+         xSnprintf(buffer, n, " N/A ");
+      }
+      break;
+   case AUTOGROUP_NICE:
+      if (lp->autogroup_id != -1) {
+         xSnprintf(buffer, n, "%3d ", lp->autogroup_nice);
+         attr = lp->autogroup_nice < 0 ? CRT_colors[PROCESS_HIGH_PRIORITY]
+              : lp->autogroup_nice > 0 ? CRT_colors[PROCESS_LOW_PRIORITY]
+              : CRT_colors[PROCESS_SHADOW];
+      } else {
+         attr = CRT_colors[PROCESS_SHADOW];
+         xSnprintf(buffer, n, "N/A ");
+      }
+      break;
    default:
       Process_writeField(this, str, field);
       return;
@@ -350,6 +402,10 @@ static int LinuxProcess_compareByKey(const Process* v1, const Process* v2, Proce
       return SPACESHIP_NUMBER(p1->ctxt_diff, p2->ctxt_diff);
    case SECATTR:
       return SPACESHIP_NULLSTR(p1->secattr, p2->secattr);
+   case AUTOGROUP_ID:
+      return SPACESHIP_NUMBER(p1->autogroup_id, p2->autogroup_id);
+   case AUTOGROUP_NICE:
+      return SPACESHIP_NUMBER(p1->autogroup_nice, p2->autogroup_nice);
    default:
       return Process_compareByKey_Base(v1, v2, key);
    }
diff --git a/linux/LinuxProcess.h b/linux/LinuxProcess.h
index 5f77db2e..bca5247a 100644
--- a/linux/LinuxProcess.h
+++ b/linux/LinuxProcess.h
@@ -28,6 +28,7 @@ in the source distribution for its full text.
 #define PROCESS_FLAG_LINUX_SECATTR   0x00008000
 #define PROCESS_FLAG_LINUX_LRS_FIX   0x00010000
 #define PROCESS_FLAG_LINUX_DELAYACCT 0x00040000
+#define PROCESS_FLAG_LINUX_AUTOGROUP 0x00080000
 
 typedef struct LinuxProcess_ {
    Process super;
@@ -99,6 +100,10 @@ typedef struct LinuxProcess_ {
    unsigned long ctxt_diff;
    char* secattr;
    unsigned long long int last_mlrs_calctime;
+
+   /* Autogroup scheduling (CFS) information */
+   long int autogroup_id;
+   int autogroup_nice;
 } LinuxProcess;
 
 extern int pageSize;
@@ -117,6 +122,10 @@ IOPriority LinuxProcess_updateIOPriority(LinuxProcess* this);
 
 bool LinuxProcess_setIOPriority(Process* this, Arg ioprio);
 
+bool LinuxProcess_isAutogroupEnabled(void);
+
+bool LinuxProcess_changeAutogroupPriorityBy(Process* this, Arg delta);
+
 bool Process_isThread(const Process* this);
 
 #endif
diff --git a/linux/LinuxProcessList.c b/linux/LinuxProcessList.c
index e1b923d6..d3463b51 100644
--- a/linux/LinuxProcessList.c
+++ b/linux/LinuxProcessList.c
@@ -909,6 +909,23 @@ static void LinuxProcessList_readOomData(LinuxProcess* process, openat_arg_t pro
    fclose(file);
 }
 
+static void LinuxProcessList_readAutogroup(LinuxProcess* process, openat_arg_t procFd) {
+   process->autogroup_id = -1;
+
+   char autogroup[64]; // space for two numeric values and fixed length strings
+   ssize_t amtRead = xReadfileat(procFd, "autogroup", autogroup, sizeof(autogroup));
+   if (amtRead < 0)
+      return;
+
+   long int identity;
+   int nice;
+   int ok = sscanf(autogroup, "/autogroup-%ld nice %d", &identity, &nice);
+   if (ok == 2) {
+      process->autogroup_id = identity;
+      process->autogroup_nice = nice;
+   }
+}
+
 static void LinuxProcessList_readCtxtData(LinuxProcess* process, openat_arg_t procFd) {
    FILE* file = fopenat(procFd, "status", "r");
    if (!file)
@@ -1521,6 +1538,10 @@ static bool LinuxProcessList_recurseProcTree(LinuxProcessList* this, openat_arg_
          LinuxProcessList_readCwd(lp, procFd);
       }
 
+      if ((settings->flags & PROCESS_FLAG_LINUX_AUTOGROUP) && this->haveAutogroup) {
+         LinuxProcessList_readAutogroup(lp, procFd);
+      }
+
       if (proc->state == 'Z' && !proc->cmdline && statCommand[0]) {
          Process_updateCmdline(proc, statCommand, 0, strlen(statCommand));
       } else if (Process_isThread(proc)) {
@@ -2071,6 +2092,16 @@ void ProcessList_goThroughEntries(ProcessList* super, bool pauseProcessUpdate) {
       return;
    }
 
+   if (settings->flags & PROCESS_FLAG_LINUX_AUTOGROUP) {
+      // Refer to sched(7) 'autogroup feature' section
+      // The kernel feature can be enabled/disabled through procfs at
+      // any time, so check for it at the start of each sample - only
+      // read from per-process procfs files if it's globally enabled.
+      this->haveAutogroup = LinuxProcess_isAutogroupEnabled();
+   } else {
+      this->haveAutogroup = false;
+   }
+
    /* PROCDIR is an absolute path */
    assert(PROCDIR[0] == '/');
 #ifdef HAVE_OPENAT
diff --git a/linux/LinuxProcessList.h b/linux/LinuxProcessList.h
index 2f296eca..0d1ad48c 100644
--- a/linux/LinuxProcessList.h
+++ b/linux/LinuxProcessList.h
@@ -71,6 +71,7 @@ typedef struct LinuxProcessList_ {
 
    TtyDriver* ttyDrivers;
    bool haveSmapsRollup;
+   bool haveAutogroup;
 
    #ifdef HAVE_DELAYACCT
    struct nl_sock* netlink_socket;
diff --git a/linux/Platform.c b/linux/Platform.c
index d23bf57d..64be93c7 100644
--- a/linux/Platform.c
+++ b/linux/Platform.c
@@ -150,8 +150,38 @@ static Htop_Reaction Platform_actionSetIOPriority(State* st) {
    return HTOP_REFRESH | HTOP_REDRAW_BAR | HTOP_UPDATE_PANELHDR;
 }
 
+static bool Platform_changeAutogroupPriority(MainPanel* panel, int delta) {
+   if (LinuxProcess_isAutogroupEnabled() == false) {
+      beep();
+      return false;
+   }
+   bool anyTagged;
+   bool ok = MainPanel_foreachProcess(panel, LinuxProcess_changeAutogroupPriorityBy, (Arg) { .i = delta }, &anyTagged);
+   if (!ok)
+      beep();
+   return anyTagged;
+}
+
+static Htop_Reaction Platform_actionHigherAutogroupPriority(State* st) {
+   if (Settings_isReadonly())
+      return HTOP_OK;
+
+   bool changed = Platform_changeAutogroupPriority(st->mainPanel, -1);
+   return changed ? HTOP_REFRESH : HTOP_OK;
+}
+
+static Htop_Reaction Platform_actionLowerAutogroupPriority(State* st) {
+   if (Settings_isReadonly())
+      return HTOP_OK;
+
+   bool changed = Platform_changeAutogroupPriority(st->mainPanel, 1);
+   return changed ? HTOP_REFRESH : HTOP_OK;
+}
+
 void Platform_setBindings(Htop_Action* keys) {
    keys['i'] = Platform_actionSetIOPriority;
+   keys['{'] = Platform_actionLowerAutogroupPriority;
+   keys['}'] = Platform_actionHigherAutogroupPriority;
 }
 
 const MeterClass* const Platform_meterTypes[] = {
diff --git a/linux/ProcessField.h b/linux/ProcessField.h
index c8d24c0b..d109ff9d 100644
--- a/linux/ProcessField.h
+++ b/linux/ProcessField.h
@@ -44,8 +44,8 @@ in the source distribution for its full text.
    M_PSSWP = 121,                \
    CTXT = 122,                   \
    SECATTR = 123,                \
-                                 \
-   DUMMY_BUMP_FIELD = CWD,       \
+   AUTOGROUP_ID = 127,           \
+   AUTOGROUP_NICE = 128,         \
    // End of list