From 71f5a80d9e312375eff28d2fbb7d8add81f6793c Mon Sep 17 00:00:00 2001
From: Ivan Shapovalov <intelfx@intelfx.name>
Date: Tue, 27 Dec 2022 05:16:54 +0400
Subject: Linux: implement zswap support

On Linux, use zswap to populate "compressed memory" metrics added in the
previous commit.

Fixes #104.
---
 linux/LinuxProcessList.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

(limited to 'linux/LinuxProcessList.c')

diff --git a/linux/LinuxProcessList.c b/linux/LinuxProcessList.c
index a3472c53..2ecdefc3 100644
--- a/linux/LinuxProcessList.c
+++ b/linux/LinuxProcessList.c
@@ -1733,6 +1733,7 @@ errorReadingProcess:
 }
 
 static inline void LinuxProcessList_scanMemoryInfo(ProcessList* this) {
+   LinuxProcessList *lpl = (LinuxProcessList *)this;
    memory_t availableMem = 0;
    memory_t freeMem = 0;
    memory_t totalMem = 0;
@@ -1743,6 +1744,8 @@ static inline void LinuxProcessList_scanMemoryInfo(ProcessList* this) {
    memory_t swapCacheMem = 0;
    memory_t swapFreeMem = 0;
    memory_t sreclaimableMem = 0;
+   memory_t zswapCompMem = 0;
+   memory_t zswapOrigMem = 0;
 
    FILE* file = fopen(PROCMEMINFOFILE, "r");
    if (!file)
@@ -1787,6 +1790,10 @@ static inline void LinuxProcessList_scanMemoryInfo(ProcessList* this) {
             break;
          }
          break;
+      case 'Z':
+         tryRead("Zswap:", zswapCompMem);
+         tryRead("Zswapped:", zswapOrigMem);
+         break;
       }
 
       #undef tryRead
@@ -1812,6 +1819,8 @@ static inline void LinuxProcessList_scanMemoryInfo(ProcessList* this) {
    this->totalSwap = swapTotalMem;
    this->usedSwap = swapTotalMem - swapFreeMem - swapCacheMem;
    this->cachedSwap = swapCacheMem;
+   lpl->zswap.usedZswapComp = zswapCompMem;
+   lpl->zswap.usedZswapOrig = zswapOrigMem;
 }
 
 static void LinuxProcessList_scanHugePages(LinuxProcessList* this) {
@@ -1870,6 +1879,24 @@ static void LinuxProcessList_scanHugePages(LinuxProcessList* this) {
    closedir(dir);
 }
 
+static inline void LinuxProcessList_scanZswapInfo(LinuxProcessList *this) {
+   long max_pool_percent = 0;
+   int r;
+   char buf[256];
+
+   r = xReadfile("/sys/module/zswap/parameters/max_pool_percent", buf, 256);
+   if (r <= 0) {
+      return;
+   }
+   max_pool_percent = strtol(buf, NULL, 10);
+   if (max_pool_percent < 0 || max_pool_percent > 100) {
+      return;
+   }
+
+   this->zswap.totalZswapPool = this->super.totalMem * max_pool_percent / 100;
+   /* the rest of the metrics are set in LinuxProcessList_scanMemoryInfo() */
+}
+
 static inline void LinuxProcessList_scanZramInfo(LinuxProcessList* this) {
    memory_t totalZram = 0;
    memory_t usedZramComp = 0;
@@ -2222,6 +2249,7 @@ void ProcessList_goThroughEntries(ProcessList* super, bool pauseProcessUpdate) {
    LinuxProcessList_scanHugePages(this);
    LinuxProcessList_scanZfsArcstats(this);
    LinuxProcessList_scanZramInfo(this);
+   LinuxProcessList_scanZswapInfo(this);
 
    double period = LinuxProcessList_scanCPUTime(super);
 
-- 
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