processes plugin: Do not gather processes IO and context switch data when unneeded

diff --git a/src/processes.c b/src/processes.c
index 4e8ca27..a29fbbc 100644 (file)
--- a/src/processes.c
+++ b/src/processes.c
@@ -185,9 +185,11 @@ typedef struct procstat_entry_s
        derive_t io_wchar;
        derive_t io_syscr;
        derive_t io_syscw;
+       _Bool    has_io;
 
        derive_t cswitch_vol;
        derive_t cswitch_invol;
+       _Bool    has_cswitch;
 
        struct procstat_entry_s *next;
 } procstat_entry_t;
@@ -241,6 +243,7 @@ static mach_msg_type_number_t     pset_list_len;
 
 #elif KERNEL_LINUX
 static long pagesize_g;
+static void ps_fill_details (const procstat_t *ps, procstat_entry_t *entry);
 /* #endif KERNEL_LINUX */
 
 #elif HAVE_LIBKVM_GETPROCS && (HAVE_STRUCT_KINFO_PROC_FREEBSD || HAVE_STRUCT_KINFO_PROC_OPENBSD)
@@ -402,6 +405,10 @@ static void ps_list_add (const char *name, const char *cmdline, procstat_entry_t
                if ((ps_list_match (name, cmdline, ps)) == 0)
                        continue;
 
+#if KERNEL_LINUX
+               ps_fill_details(ps, entry);
+#endif
+
                for (pse = ps->instances; pse != NULL; pse = pse->next)
                        if ((pse->id == entry->id) || (pse->next == NULL))
                                break;
@@ -793,7 +800,7 @@ static void ps_submit_fork_rate (derive_t value)
 
 /* ------- additional functions for KERNEL_LINUX/HAVE_THREAD_INFO ------- */
 #if KERNEL_LINUX
-static procstat_t *ps_read_tasks_status (long pid, procstat_t *ps)
+static int ps_read_tasks_status (procstat_entry_t *ps)
 {
        char           dirname[64];
        DIR           *dh;
@@ -806,12 +813,12 @@ static procstat_t *ps_read_tasks_status (long pid, procstat_t *ps)
        char *fields[8];
        int numfields;
 
-       ssnprintf (dirname, sizeof (dirname), "/proc/%li/task", pid);
+       ssnprintf (dirname, sizeof (dirname), "/proc/%li/task", ps->id);
 
        if ((dh = opendir (dirname)) == NULL)
        {
                DEBUG ("Failed to open directory `%s'", dirname);
-               return (NULL);
+               return (-1);
        }
 
        while ((ent = readdir (dh)) != NULL)
@@ -823,7 +830,7 @@ static procstat_t *ps_read_tasks_status (long pid, procstat_t *ps)
 
                tpid = ent->d_name;
 
-               ssnprintf (filename, sizeof (filename), "/proc/%li/task/%s/status", pid, tpid);
+               ssnprintf (filename, sizeof (filename), "/proc/%li/task/%s/status", ps->id, tpid);
                if ((fh = fopen (filename, "r")) == NULL)
                {
                        DEBUG ("Failed to open file `%s'", filename);
@@ -873,7 +880,7 @@ static procstat_t *ps_read_tasks_status (long pid, procstat_t *ps)
        ps->cswitch_vol = cswitch_vol;
        ps->cswitch_invol = cswitch_invol;
 
-       return (ps);
+       return (0);
 } /* int *ps_read_tasks_status */
 
 /* Read data from /proc/pid/status */
@@ -947,7 +954,7 @@ static procstat_t *ps_read_status (long pid, procstat_t *ps)
        return (ps);
 } /* procstat_t *ps_read_vmem */
 
-static procstat_t *ps_read_io (long pid, procstat_t *ps)
+static int ps_read_io (procstat_entry_t *ps)
 {
        FILE *fh;
        char buffer[1024];
@@ -956,9 +963,9 @@ static procstat_t *ps_read_io (long pid, procstat_t *ps)
        char *fields[8];
        int numfields;
 
-       ssnprintf (filename, sizeof (filename), "/proc/%li/io", pid);
+       ssnprintf (filename, sizeof (filename), "/proc/%li/io", ps->id);
        if ((fh = fopen (filename, "r")) == NULL)
-               return (NULL);
+               return (-1);
 
        while (fgets (buffer, sizeof (buffer), fh) != NULL)
        {
@@ -998,9 +1005,36 @@ static procstat_t *ps_read_io (long pid, procstat_t *ps)
                WARNING ("processes: fclose: %s",
                                sstrerror (errno, errbuf, sizeof (errbuf)));
        }
+       return (0);
+} /* int ps_read_io (...) */
 
-       return (ps);
-} /* procstat_t *ps_read_io */
+static void ps_fill_details (const procstat_t *ps, procstat_entry_t *entry)
+{
+       if ( entry->has_io == 0 && ps_read_io (entry) != 0 )
+       {
+               /* no io data */
+               entry->io_rchar = -1;
+               entry->io_wchar = -1;
+               entry->io_syscr = -1;
+               entry->io_syscw = -1;
+
+               DEBUG("ps_read_process: not get io data for pid %li", entry->id);
+       }
+       entry->has_io = 1;
+
+       if ( report_ctx_switch )
+       {
+               if ( entry->has_cswitch == 0 && ps_read_tasks_status(entry) != 0 )
+               {
+                       entry->cswitch_vol = -1;
+                       entry->cswitch_invol = -1;
+
+                       DEBUG("ps_read_tasks_status: not get context "
+                                       "switch data for pid %li", entry->id);
+               }
+               entry->has_cswitch = 1;
+       }
+} /* void ps_fill_details (...) */
 
 static int ps_read_process (long pid, procstat_t *ps, char *state)
 {
@@ -1133,29 +1167,6 @@ static int ps_read_process (long pid, procstat_t *ps, char *state)
        ps->vmem_rss = (unsigned long) vmem_rss;
        ps->stack_size = (unsigned long) stack_size;
 
-       if ( (ps_read_io (pid, ps)) == NULL)
-       {
-               /* no io data */
-               ps->io_rchar = -1;
-               ps->io_wchar = -1;
-               ps->io_syscr = -1;
-               ps->io_syscw = -1;
-
-               DEBUG("ps_read_process: not get io data for pid %li", pid);
-       }
-
-       if ( report_ctx_switch )
-       {
-               if ( (ps_read_tasks_status(pid, ps)) == NULL)
-               {
-                       ps->cswitch_vol = -1;
-                       ps->cswitch_invol = -1;
-
-                       DEBUG("ps_read_tasks_status: not get context "
-                                       "switch data for pid %li", pid);
-               }
-       }
-
        /* success */
        return (0);
 } /* int ps_read_process (...) */