PCP platform implementation of frontswap and zswap accounting

4 files changed, 46 insertions, 3 deletions

diff --git a/pcp/Metric.h b/pcp/Metric.h
index 789ef4b2..914d7d65 100644
--- a/pcp/Metric.h
+++ b/pcp/Metric.h
@@ -93,6 +93,9 @@ typedef enum Metric_ {
    PCP_ZRAM_CAPACITY,           /* zram.capacity */
    PCP_ZRAM_ORIGINAL,           /* zram.mm_stat.data_size.original */
    PCP_ZRAM_COMPRESSED,         /* zram.mm_stat.data_size.compressed */
+   PCP_ZSWAP_MAX_POOL_PERCENT,  /* sysfs.module.zswap.max_pool_percent */
+   PCP_MEM_ZSWAP,               /* mem.util.zswap */
+   PCP_MEM_ZSWAPPED,            /* mem.util.zswapped */
    PCP_VFS_FILES_COUNT,         /* vfs.files.count */
    PCP_VFS_FILES_MAX,           /* vfs.files.max */
 
diff --git a/pcp/PCPMachine.c b/pcp/PCPMachine.c
index 5f24a284..faf3ae96 100644
--- a/pcp/PCPMachine.c
+++ b/pcp/PCPMachine.c
@@ -178,6 +178,19 @@ static void PCPMachine_updatePerCPUReal(PCPMachine* this, Metric metric, CPUMetr
       this->percpu[i][cpumetric].d = this->values[i].d;
 }
 
+static inline void PCPMachine_scanZswapInfo(PCPMachine* this) {
+   const Machine* host = &this->super;
+   pmAtomValue value;
+
+   memset(&this->zswap, 0, sizeof(ZswapStats));
+   if (Metric_values(PCP_ZSWAP_MAX_POOL_PERCENT, &value, 1, PM_TYPE_U64))
+      this->zswap.totalZswapPool = host->totalMem * value.ull / 100;
+   if (Metric_values(PCP_MEM_ZSWAP, &value, 1, PM_TYPE_U64))
+      this->zswap.usedZswapComp = value.ull;
+   if (Metric_values(PCP_MEM_ZSWAPPED, &value, 1, PM_TYPE_U64))
+      this->zswap.usedZswapOrig = value.ull;
+}
+
 static inline void PCPMachine_scanZfsArcstats(PCPMachine* this) {
    unsigned long long int dbufSize = 0;
    unsigned long long int dnodeSize = 0;
@@ -251,6 +264,7 @@ static void PCPMachine_scan(PCPMachine* this) {
       PCPMachine_updatePerCPUReal(this, PCP_HINV_CPUCLOCK, CPU_FREQUENCY);
 
    PCPMachine_scanZfsArcstats(this);
+   PCPMachine_scanZswapInfo(this);
 }
 
 void Machine_scan(Machine* super) {
diff --git a/pcp/PCPMachine.h b/pcp/PCPMachine.h
index faca8efc..fe6c503f 100644
--- a/pcp/PCPMachine.h
+++ b/pcp/PCPMachine.h
@@ -17,6 +17,7 @@ in the source distribution for its full text.
 #include "UsersTable.h"
 
 #include "pcp/Platform.h"
+#include "linux/ZswapStats.h"
 #include "zfs/ZfsArcStats.h"
 
 
@@ -59,10 +60,14 @@ typedef struct PCPMachine_ {
    int smaps_flag;
    double period;
    double timestamp;     /* previous sample timestamp */
+
    pmAtomValue* cpu;     /* aggregate values for each metric */
    pmAtomValue** percpu; /* per-processor values for each metric */
    pmAtomValue* values;  /* per-processor buffer for just one metric */
+
    ZfsArcStats zfs;
+   /*ZramStats zram; -- not needed, calculated in-line in Platform.c */
+   ZswapStats zswap;
 } PCPMachine;
 
 #endif
diff --git a/pcp/Platform.c b/pcp/Platform.c
index 9fb3770e..402276ae 100644
--- a/pcp/Platform.c
+++ b/pcp/Platform.c
@@ -197,6 +197,9 @@ static const char* Platform_metricNames[] = {
    [PCP_ZRAM_CAPACITY] = "zram.capacity",
    [PCP_ZRAM_ORIGINAL] = "zram.mm_stat.data_size.original",
    [PCP_ZRAM_COMPRESSED] = "zram.mm_stat.data_size.compressed",
+   [PCP_ZSWAP_MAX_POOL_PERCENT] = "sysfs.module.zswap.max_pool_percent",
+   [PCP_MEM_ZSWAP] = "mem.util.zswap",
+   [PCP_MEM_ZSWAPPED] = "mem.util.zswapped",
    [PCP_VFS_FILES_COUNT] = "vfs.files.count",
    [PCP_VFS_FILES_MAX] = "vfs.files.max",
 
@@ -549,9 +552,9 @@ void Platform_setMemoryValues(Meter* this) {
 
    this->total = host->totalMem;
    this->values[MEMORY_METER_USED] = host->usedMem;
-   this->values[MEMORY_METER_BUFFERS] = host->buffersMem;
    this->values[MEMORY_METER_SHARED] = host->sharedMem;
-   // this->values[MEMORY_METER_COMPRESSED] = "compressed memory, like zswap on linux"
+   this->values[MEMORY_METER_COMPRESSED] = 0;
+   this->values[MEMORY_METER_BUFFERS] = host->buffersMem;
    this->values[MEMORY_METER_CACHE] = host->cachedMem;
    this->values[MEMORY_METER_AVAILABLE] = host->availableMem;
 
@@ -564,14 +567,32 @@ void Platform_setMemoryValues(Meter* this) {
       this->values[MEMORY_METER_CACHE] += shrinkableSize;
       this->values[MEMORY_METER_AVAILABLE] += shrinkableSize;
    }
+
+   if (phost->zswap.usedZswapOrig > 0 || phost->zswap.usedZswapComp > 0) {
+      this->values[MEMORY_METER_USED] -= phost->zswap.usedZswapComp;
+      this->values[MEMORY_METER_COMPRESSED] += phost->zswap.usedZswapComp;
+   }
 }
 
 void Platform_setSwapValues(Meter* this) {
    const Machine* host = this->host;
+   const PCPMachine* phost = (const PCPMachine*) host;
+
    this->total = host->totalSwap;
    this->values[SWAP_METER_USED] = host->usedSwap;
    this->values[SWAP_METER_CACHE] = host->cachedSwap;
-   // this->values[SWAP_METER_FRONTSWAP] = "pages that are accounted to swap but stored elsewhere, like frontswap on linux"
+   this->values[SWAP_METER_FRONTSWAP] = 0; /* frontswap -- memory that is accounted to swap but resides elsewhere */
+
+   if (phost->zswap.usedZswapOrig > 0 || phost->zswap.usedZswapComp > 0) {
+      /* refer to linux/Platform.c::Platform_setSwapValues for details */
+      this->values[SWAP_METER_USED] -= phost->zswap.usedZswapOrig;
+      if (this->values[SWAP_METER_USED] < 0) {
+         /* subtract the overflow from SwapCached */
+         this->values[SWAP_METER_CACHE] += this->values[SWAP_METER_USED];
+         this->values[SWAP_METER_USED] = 0;
+      }
+      this->values[SWAP_METER_FRONTSWAP] += phost->zswap.usedZswapOrig;
+   }
 }
 
 void Platform_setZramValues(Meter* this) {