Read system swappiness in omrsysinfo_get_memory_info()

The code read swappiness value on Linux and sets OMRPORT_MEMINFO_NOT_AVAILABLE if the value is not available. The system wide swappiness value specified at /proc/sys/vm/swappiness for vm.swappiness is read. Closes: eclipse-omr#5237 Signed-off-by: SajinaKandy <[email protected]>
dmitripivkine · Oct 11, 2023 · ba1e956 · ba1e956
1 parent 612cde0
commit ba1e956
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diff --git a/fvtest/porttest/si.cpp b/fvtest/porttest/si.cpp
@@ -1299,6 +1299,9 @@ TEST(PortSysinfoTest, sysinfo_testMemoryInfo)
 #else /* defined (OSX) */
 			|| (OMRPORT_MEMINFO_NOT_AVAILABLE == memInfo.cached)
 #endif /* defined(OSX) */
+#if defined (LINUX)
+			|| (OMRPORT_MEMINFO_NOT_AVAILABLE == memInfo.swappiness)
+#endif /* defined(LINUX) */
 		) {
 
 			/* Fail pltest if one of these memory usage parameters were found inconsistent. */

diff --git a/include_core/omrport.h b/include_core/omrport.h
@@ -748,6 +748,11 @@ typedef struct J9MemoryInfo {
 	 * When not in a cgroup, this will be identical to 'buffered' field above.
 	 */
 	uint64_t hostBuffered;
+	/* The default setting for this kernel parameter of swappiness is 60. Value of 0 disables swap.
+	 * Lower swappiness values would keep more pages in memory instead of putting them in swap space.
+	 * Higher values will provide more I/O cache and lower values will wait longer to swap out idle application.
+	 */
+	uint64_t swappiness;
 } J9MemoryInfo;
 
 #define OMRPORT_MEMINFO_NOT_AVAILABLE ((uint64_t) -1)

diff --git a/include_core/omrporterror.h b/include_core/omrporterror.h
@@ -418,6 +418,8 @@
 #define OMRPORT_ERROR_SYSINFO_CGROUP_VERSION_NOT_AVAILABLE (OMRPORT_ERROR_SYSINFO_BASE-28)
 #define OMRPORT_ERROR_SYSINFO_CGROUP_FILENAME_INVALID (OMRPORT_ERROR_SYSINFO_BASE-29)
 #define OMRPORT_ERROR_SYSINFO_CGROUP_NULL_PARAM (OMRPORT_ERROR_SYSINFO_BASE-30)
+#define OMRPORT_ERROR_SYSINFO_ERROR_SWAPPINESS_OPEN_FAILED (OMRPORT_ERROR_SYSINFO_BASE-31)
+#define OMRPORT_ERROR_SYSINFO_ERROR_READING_SWAPPINESS (OMRPORT_ERROR_SYSINFO_BASE-32)
 
 /**
  * @name Port library initialization return codes

diff --git a/port/common/omrport.tdf b/port/common/omrport.tdf
@@ -1626,3 +1626,7 @@ TraceExit-Exception=Trc_PRT_mmap_map_file_unix_filestatfailed_exit Group=mmap Ov
 TraceExit-Exception=Trc_PRT_mmap_map_file_cannotallocatehandle_exit Group=mmap Overhead=1 Level=1 NoEnv Template="omrmmap_map_file: Could not allocate memory for handle"
 
 TraceEvent=Trc_PRT_sl_open_shared_library_noload Group=sl Overhead=1 Level=3 NoEnv Template="omrsl_open_shared_library tests if a library is already loaded, returns handle=%p"
+
+TraceException=Trc_PRT_retrieveLinuxMemoryStats_failedOpeningSwappinessFs Group=sysinfo Overhead=1 Level=1 NoEnv Template="retrieveLinuxMemoryStats: Failed to open /proc/sys/vm/swappiness. Error code = %d."
+TraceException=Trc_PRT_retrieveLinuxMemoryStats_failedReadingSwappiness Group=sysinfo Overhead=1 Level=1 NoEnv Template="retrieveLinuxMemoryStats: Failed to read /proc/sys/vm/swappiness. Error code = %d."
+TraceException=Trc_PRT_retrieveLinuxMemoryStats_unexpectedSwappinessFormat Group=sysinfo Overhead=1 Level=1 NoEnv Template="retrieveLinuxMemoryStats: Expected %d items to read, but read %d items."
diff --git a/port/unix/omrsysinfo.c b/port/unix/omrsysinfo.c
@@ -398,6 +398,7 @@ struct {
 
 /* Cgroup v1 and v2 memory files */
 #define CGROUP_MEMORY_STAT_FILE "memory.stat"
+#define CGROUP_MEMORY_SWAPPINESS "memory.swappiness"
 
 /* Cgroup v1 memory files */
 #define CGROUP_MEMORY_LIMIT_IN_BYTES_FILE "memory.limit_in_bytes"
@@ -3257,6 +3258,8 @@ omrsysinfo_get_number_CPUs_by_type(struct OMRPortLibrary *portLibrary, uintptr_t
 #define BUFFERS_PREFIX      "Buffers:"
 #define BUFFERS_PREFIX_SZ   (sizeof(BUFFERS_PREFIX) - 1)
 
+#define PROC_SYS_VM_SWAPPINESS "/proc/sys/vm/swappiness"
+
 /**
  * Function collects memory usage statistics by reading /proc/meminfo on Linux platforms.
  *
@@ -3269,7 +3272,9 @@ static int32_t
 retrieveLinuxMemoryStatsFromProcFS(struct OMRPortLibrary *portLibrary, struct J9MemoryInfo *memInfo)
 {
 	int32_t rc = 0;
+	int32_t rcSwappiness = 0;
 	FILE *memStatFs = NULL;
+	FILE *swappinessFs = NULL;
 	char lineString[MAX_LINE_LENGTH] = {0};
 
 	/* Open the memstat file on Linux for reading; this is readonly. */
@@ -3380,6 +3385,24 @@ retrieveLinuxMemoryStatsFromProcFS(struct OMRPortLibrary *portLibrary, struct J9
 		} /* end if else-if */
 	} /* end while() */
 
+	swappinessFs = fopen(PROC_SYS_VM_SWAPPINESS, "r");
+	if (NULL == swappinessFs) {
+		Trc_PRT_retrieveLinuxMemoryStats_failedOpeningSwappinessFs(errno);
+		rc = OMRPORT_ERROR_SYSINFO_ERROR_SWAPPINESS_OPEN_FAILED;
+		goto _cleanup;
+	}
+
+	rcSwappiness = fscanf(swappinessFs, "%" SCNu64, &memInfo->swappiness);
+	if (1 != rcSwappiness) {
+		if (EOF == rcSwappiness) {
+			Trc_PRT_retrieveLinuxMemoryStats_failedReadingSwappiness(errno);
+		} else {
+			Trc_PRT_retrieveLinuxMemoryStats_unexpectedSwappinessFormat(1, rcSwappiness);
+		}
+		rc = OMRPORT_ERROR_SYSINFO_ERROR_READING_SWAPPINESS;
+		goto _cleanup;
+	}
+
 	/* Set hostXXX fields with memory stats from proc fs.
 	 * These may be used for calculating available physical memory on the host.
 	 */
@@ -3391,6 +3414,9 @@ retrieveLinuxMemoryStatsFromProcFS(struct OMRPortLibrary *portLibrary, struct J9
 	if (NULL != memStatFs) {
 		fclose(memStatFs);
 	}
+	if (NULL != swappinessFs) {
+		fclose(swappinessFs);
+	}
 
 	return rc;
 }
@@ -3482,6 +3508,11 @@ retrieveLinuxCgroupMemoryStats(struct OMRPortLibrary *portLibrary, struct OMRCgr
 		cgroupMemInfo->memoryAndSwapUsage += cgroupMemInfo->memoryUsage;
 	}
 
+	rc = readCgroupSubsystemFile(portLibrary, OMR_CGROUP_SUBSYSTEM_MEMORY, CGROUP_MEMORY_SWAPPINESS, numItemsToRead, "%" SCNu64, &cgroupMemInfo->swappiness);
+	if (0 != rc) {
+		goto _exit;
+	}
+
 	/* Read value of page cache memory from memory.stat file */
 	rc = getHandleOfCgroupSubsystemFile(portLibrary, OMR_CGROUP_SUBSYSTEM_MEMORY, CGROUP_MEMORY_STAT_FILE, &memStatFs);
 	if (0 != rc) {
@@ -3607,6 +3638,7 @@ retrieveLinuxMemoryStats(struct OMRPortLibrary *portLibrary, struct J9MemoryInfo
 		}
 	}
 
+	memInfo->swappiness = cgroupMemInfo.swappiness;
 	memInfo->cached = cgroupMemInfo.cached;
 	/* Buffered value is not available when running in a cgroup.
 	 * See https://www.kernel.org/doc/Documentation/cgroup-v1/memory.txt
@@ -3771,6 +3803,7 @@ omrsysinfo_get_memory_info(struct OMRPortLibrary *portLibrary, struct J9MemoryIn
 	memInfo->availSwap = OMRPORT_MEMINFO_NOT_AVAILABLE;
 	memInfo->cached = OMRPORT_MEMINFO_NOT_AVAILABLE;
 	memInfo->buffered = OMRPORT_MEMINFO_NOT_AVAILABLE;
+	memInfo->swappiness = OMRPORT_MEMINFO_NOT_AVAILABLE;
 
 	memInfo->hostAvailPhysical = OMRPORT_MEMINFO_NOT_AVAILABLE;
 	memInfo->hostCached = OMRPORT_MEMINFO_NOT_AVAILABLE;

diff --git a/port/unix_include/omrcgroup.h b/port/unix_include/omrcgroup.h
@@ -36,6 +36,7 @@ typedef struct OMRCgroupMemoryInfo {
 	uint64_t memoryUsage; /**< current memory usage in bytes (as in memory.usage_in_bytes file)*/
 	uint64_t memoryAndSwapLimit; /**< memory + swap limit in bytes (as in memory.memsw.limit_in_bytes file)*/
 	uint64_t memoryAndSwapUsage; /**< current memory + swap usage in bytes (as in memory.memsw.usage_in_bytes file) */
+	uint64_t swappiness; /**< indicates kernel aggressiveness (0-100) in swapping memory pages for cgroups, and is not supported on cgroups V2 */
 	uint64_t cached; /**< page cache memory (as in memory.stat file)*/
 } OMRCgroupMemoryInfo;
 

diff --git a/port/win32/omrsysinfo.c b/port/win32/omrsysinfo.c
@@ -901,6 +901,7 @@ omrsysinfo_get_memory_info(struct OMRPortLibrary *portLibrary, struct J9MemoryIn
 	memInfo->availSwap = OMRPORT_MEMINFO_NOT_AVAILABLE;
 	memInfo->cached = OMRPORT_MEMINFO_NOT_AVAILABLE;
 	memInfo->buffered = OMRPORT_MEMINFO_NOT_AVAILABLE;
+	memInfo->swappiness = OMRPORT_MEMINFO_NOT_AVAILABLE;
 
 	aMemStatusEx.dwLength = sizeof(aMemStatusEx);
 	rc = GlobalMemoryStatusEx(&aMemStatusEx);