issue: 3884801 Add XLIO_QUICK_START parameter

The parameter disables the check for resident hugepages. The check can
be expensive and, on the other hand, can be irrelevant based on the
system configuration. Therefore, disabling it reduces the initialization
time which can be crucial in some scenarios.

The name for the parameter is chosen to extend the idea of reducing
initialization time in the future.

Signed-off-by: Dmytro Podgornyi <[email protected]>

README

@@ -79,6 +79,7 @@ Example:
  XLIO DETAILS: SigIntr Ctrl-C Handle          Enabled                    [XLIO_HANDLE_SIGINTR]
  XLIO DETAILS: SegFault Backtrace             Disabled                   [XLIO_HANDLE_SIGSEGV]
  XLIO DETAILS: Print a report                 Disabled                   [XLIO_PRINT_REPORT]
+ XLIO DETAILS: Quick start                    Disabled                   [XLIO_QUICK_START]
  XLIO DETAILS: Ring allocation logic TX       0 (Ring per interface)     [XLIO_RING_ALLOCATION_LOGIC_TX]
  XLIO DETAILS: Ring allocation logic RX       0 (Ring per interface)     [XLIO_RING_ALLOCATION_LOGIC_RX]
  XLIO INFO   : Ring migration ratio TX        -1                         [XLIO_RING_MIGRATION_RATIO_TX]
@@ -308,6 +309,13 @@ When Enabled, print backtrace if segmentation fault happens.
 Value range is 0 to 1
 Default value is 0 (Disabled)
 
+XLIO_QUICK_START
+Avoid expensive extra checks to reduce the initialization time. This may result
+in failures in case of a system misconfiguration.
+For example, if the parameter is enabled and hugepages are requested beyond the
+cgroup limit, XLIO crashes due to an access to an unmapped page.
+Default value is 0 (Disabled)
+
 XLIO_ZC_BUFS
 Number of global zerocopy data buffer elements allocation.
 Default value is 200000

src/core/main.cpp

@@ -501,6 +501,8 @@ void print_xlio_global_settings()
                       safe_mce_sys().handle_segfault ? "Enabled " : "Disabled");
     VLOG_PARAM_STRING("Print a report", safe_mce_sys().print_report, MCE_DEFAULT_PRINT_REPORT,
                       SYS_VAR_PRINT_REPORT, safe_mce_sys().print_report ? "Enabled " : "Disabled");
+    VLOG_PARAM_STRING("Quick start", safe_mce_sys().quick_start, MCE_DEFAULT_QUICK_START,
+                      SYS_VAR_QUICK_START, safe_mce_sys().quick_start ? "Enabled " : "Disabled");
 
     VLOG_PARAM_NUMSTR("Ring allocation logic TX", safe_mce_sys().ring_allocation_logic_tx,
                       MCE_DEFAULT_RING_ALLOCATION_LOGIC_TX, SYS_VAR_RING_ALLOCATION_LOGIC_TX,

src/core/util/hugepage_mgr.cpp

@@ -114,7 +114,7 @@ void *hugepage_mgr::alloc_hugepages_helper(size_t &size, size_t hugepage)
     if (ptr == MAP_FAILED) {
         ptr = nullptr;
         __log_info_dbg("mmap failed (errno=%d), skipping hugepage %zu kB", errno, hugepage / 1024U);
-    } else {
+    } else if (!safe_mce_sys().quick_start) {
         /* Check whether all the pages are resident. In a container, allocation beyond the limit can
          * be successful and lead to SIGBUS on an access.
          */
@@ -148,11 +148,12 @@ void *hugepage_mgr::alloc_hugepages_helper(size_t &size, size_t hugepage)
             __log_info_dbg("Cannot use hugepages, skipping hugepage %zu kB", hugepage / 1024U);
 
             ptr = nullptr;
-        } else {
-            // Success.
-            size = actual_size;
         }
     }
+    if (ptr) {
+        // Success.
+        size = actual_size;
+    }
     return ptr;
 }
 

src/core/util/sys_vars.cpp

@@ -761,6 +761,7 @@ void mce_sys_var::get_env_params()
     service_enable = MCE_DEFAULT_SERVICE_ENABLE;
 
     print_report = MCE_DEFAULT_PRINT_REPORT;
+    quick_start = MCE_DEFAULT_QUICK_START;
     log_level = VLOG_DEFAULT;
     log_details = MCE_DEFAULT_LOG_DETAILS;
     log_colors = MCE_DEFAULT_LOG_COLORS;
@@ -1084,6 +1085,10 @@ void mce_sys_var::get_env_params()
         print_report = atoi(env_ptr) ? true : false;
     }
 
+    if ((env_ptr = getenv(SYS_VAR_QUICK_START))) {
+        quick_start = atoi(env_ptr) ? true : false;
+    }
+
     if ((env_ptr = getenv(SYS_VAR_LOG_FILENAME))) {
         read_env_variable_with_pid(log_filename, sizeof(log_filename), env_ptr);
     }

src/core/util/sys_vars.h

@@ -340,6 +340,7 @@ struct mce_sys_var {
     uint32_t mce_spec;
 
     bool print_report;
+    bool quick_start;
     vlog_levels_t log_level;
     uint32_t log_details;
     char log_filename[PATH_MAX];
@@ -558,6 +559,7 @@ extern mce_sys_var &safe_mce_sys();
 #define SYS_VAR_HANDLE_SIGINTR      "XLIO_HANDLE_SIGINTR"
 #define SYS_VAR_HANDLE_SIGSEGV      "XLIO_HANDLE_SIGSEGV"
 #define SYS_VAR_STATS_FD_NUM        "XLIO_STATS_FD_NUM"
+#define SYS_VAR_QUICK_START         "XLIO_QUICK_START"
 
 #define SYS_VAR_RING_ALLOCATION_LOGIC_TX "XLIO_RING_ALLOCATION_LOGIC_TX"
 #define SYS_VAR_RING_ALLOCATION_LOGIC_RX "XLIO_RING_ALLOCATION_LOGIC_RX"
@@ -710,7 +712,8 @@ extern mce_sys_var &safe_mce_sys();
 #define MCE_DEFAULT_APP_ID                   ("XLIO_DEFAULT_APPLICATION_ID")
 #define MCE_DEFAULT_HANDLE_SIGINTR           (true)
 #define MCE_DEFAULT_HANDLE_SIGFAULT          (false)
-#define MCE_DEFAULT_STATS_FD_NUM             0
+#define MCE_DEFAULT_STATS_FD_NUM             (0)
+#define MCE_DEFAULT_QUICK_START              (false)
 #define MCE_DEFAULT_RING_ALLOCATION_LOGIC_TX (RING_LOGIC_PER_THREAD)
 #define MCE_DEFAULT_RING_ALLOCATION_LOGIC_RX (RING_LOGIC_PER_THREAD)
 #define MCE_DEFAULT_RING_MIGRATION_RATIO_TX  (-1)