Linux: Use /proc/*/smaps_rollup for improved PSS parsing speed

2 files changed, 18 insertions, 3 deletions

diff --git a/linux/LinuxProcessList.c b/linux/LinuxProcessList.c
index a02da072..c1ccd420 100644
--- a/linux/LinuxProcessList.c
+++ b/linux/LinuxProcessList.c
@@ -89,6 +89,7 @@ typedef struct LinuxProcessList_ {
    
    CPUData* cpus;
    TtyDriver* ttyDrivers;
+   bool haveSmapsRollup;
    
    #ifdef HAVE_DELAYACCT
    struct nl_sock *netlink_socket;
@@ -240,8 +241,17 @@ ProcessList* ProcessList_new(UsersTable* usersTable, Hashtable* pidWhiteList, ui
    LinuxProcessList_initNetlinkSocket(this);
    #endif
 
+   // Check for /proc/*/smaps_rollup availability (improves smaps parsing speed, Linux 4.14+)
+   FILE* file = fopen(PROCDIR "/self/smaps_rollup", "r");
+   if(file != NULL) {
+      this->haveSmapsRollup = true;
+      fclose(file);
+   } else {
+      this->haveSmapsRollup = false;
+   }
+
    // Update CPU count:
-   FILE* file = fopen(PROCSTATFILE, "r");
+   file = fopen(PROCSTATFILE, "r");
    if (file == NULL) {
       CRT_fatalError("Cannot open " PROCSTATFILE);
    }
@@ -486,7 +496,7 @@ static bool LinuxProcessList_readStatmFile(LinuxProcess* process, const char* di
    return (errno == 0);
 }
 
-static bool LinuxProcessList_readSmapsFile(LinuxProcess* process, const char* dirname, const char* name) {
+static bool LinuxProcessList_readSmapsFile(LinuxProcess* process, const char* dirname, const char* name, bool haveSmapsRollup) {
    //http://elixir.free-electrons.com/linux/v4.10/source/fs/proc/task_mmu.c#L719
    //kernel will return data in chunks of size PAGE_SIZE or less.
 
@@ -494,7 +504,11 @@ static bool LinuxProcessList_readSmapsFile(LinuxProcess* process, const char* di
    char *start,*end;
    ssize_t nread=0;
    int tmp=0;
+   if(haveSmapsRollup) {// only available in Linux 4.14+
+      snprintf(buffer, MAX_NAME, "%s/%s/smaps_rollup", dirname, name);
+   } else {
    snprintf(buffer, MAX_NAME, "%s/%s/smaps", dirname, name);
+   }
    int fd = open(buffer, O_RDONLY);
    if (fd == -1)
       return false;
@@ -872,7 +886,7 @@ static bool LinuxProcessList_recurseProcTree(LinuxProcessList* this, const char*
             // Read smaps file of each process only every second pass to improve performance
             static int smaps_flag = 0;
             if ((pid & 1) == smaps_flag){
-               LinuxProcessList_readSmapsFile(lp, dirname, name);
+              LinuxProcessList_readSmapsFile(lp, dirname, name, this->haveSmapsRollup);
             }
             if (pid == 1) {
                smaps_flag = !smaps_flag;
diff --git a/linux/LinuxProcessList.h b/linux/LinuxProcessList.h
index f30b487d..59e83bcb 100644
--- a/linux/LinuxProcessList.h
+++ b/linux/LinuxProcessList.h
@@ -62,6 +62,7 @@ typedef struct LinuxProcessList_ {
    
    CPUData* cpus;
    TtyDriver* ttyDrivers;
+   bool haveSmapsRollup;
    
    #ifdef HAVE_DELAYACCT
    struct nl_sock *netlink_socket;