Added logging of system memory in bytes and fixed calculations to com…

…pare in unit of bytes

presto-native-execution/presto_cpp/main/LinuxMemoryChecker.cpp

@@ -85,18 +85,25 @@ class LinuxMemoryChecker : public PeriodicMemoryChecker {
   void start() {
     // Check system-memory-gb < system-mem-limit-gb < actual total memory
     // capacity.
+    auto* systemConfig = SystemConfig::instance();
+    int64_t systemMemoryInBytes = systemConfig->systemMemoryGb() << 30;
+    LOG(INFO) << fmt::format("System memory in bytes: {}", systemMemoryInBytes);
+
+    LOG(INFO) << fmt::format(
+        "System memory limit in bytes: {}", config_.systemMemLimitBytes);
+
     int64_t actualTotalMemory = getActualTotalMemory();
     LOG(INFO) << fmt::format(
         "Actual total memory in bytes: {}", actualTotalMemory);
+
     VELOX_CHECK_LE(
         config_.systemMemLimitBytes,
         actualTotalMemory,
         "system memory limit = {} bytes is higher than the actual total memory capacity = {} bytes.",
         config_.systemMemLimitBytes,
         actualTotalMemory);
 
-    auto* systemConfig = SystemConfig::instance();
-    if (config_.systemMemLimitBytes < systemConfig->systemMemoryGb()) {
+    if (config_.systemMemLimitBytes < systemMemoryInBytes) {
       LOG(WARNING) << "system-mem-limit-gb is smaller than system-memory-gb. "
                    << "Expected: system-mem-limit-gb >= system-memory-gb.";
     }
@@ -108,6 +115,7 @@ class LinuxMemoryChecker : public PeriodicMemoryChecker {
     // Set actual total memory to be the smaller number between /proc/meminfo
     // and memMaxFile_.
     int64_t actualTotalMemory = 0;
+    // meminfo's units is in kB.
     folly::gen::byLine(memInfoFile_.c_str()) |
         [&](const folly::StringPiece& line) -> void {
       if (actualTotalMemory != 0) {
@@ -140,6 +148,7 @@ class LinuxMemoryChecker : public PeriodicMemoryChecker {
       };
     }
 
+    // Unit is in bytes.
     return actualTotalMemory;
   }