From a7384483a4e9bc99009cfbf1f2898394ad4222ac Mon Sep 17 00:00:00 2001
From: Matt Ickstadt <matt@beckenterprises.com>
Date: Fri, 29 Apr 2022 22:08:00 -0500
Subject: [PATCH] Include ZFS ARC in cached/available memory on Linux

---
 src/btop_config.cpp        |  3 +++
 src/btop_menu.cpp          |  9 +++++++++
 src/linux/btop_collect.cpp | 22 ++++++++++++++++++++++
 3 files changed, 34 insertions(+)

diff --git a/src/btop_config.cpp b/src/btop_config.cpp
index 61476e1..137b168 100644
--- a/src/btop_config.cpp
+++ b/src/btop_config.cpp
@@ -141,6 +141,8 @@ namespace Config {
 
 		{"mem_below_net",		"#* Show mem box below net box instead of above."},
 
+		{"zfs_arc_cached",		"#* Count ZFS ARC in cached and available memory."},
+
 		{"show_swap", 			"#* If swap memory should be shown in memory box."},
 
 		{"swap_disk", 			"#* Show swap as a disk, ignores show_swap value above, inserts itself after first disk."},
@@ -230,6 +232,7 @@ namespace Config {
 		{"background_update", true},
 		{"mem_graphs", true},
 		{"mem_below_net", false},
+		{"zfs_arc_cached", true},
 		{"show_swap", true},
 		{"swap_disk", true},
 		{"show_disks", true},
diff --git a/src/btop_menu.cpp b/src/btop_menu.cpp
index 92aea75..65d1639 100644
--- a/src/btop_menu.cpp
+++ b/src/btop_menu.cpp
@@ -490,6 +490,15 @@ namespace Menu {
 				"",
 				"Example:",
 				"\"exclude=/boot /home/user\""},
+			{"zfs_arc_cached",
+				"(Linux) Count ZFS ARC as cached memory.",
+				"",
+				"Add ZFS ARC used to cached memory and",
+				"ZFS ARC available to available memory.",
+				"These are otherwise reported by the Linux",
+				"kernel as used memory.",
+				"",
+				"True or False."},
 		},
 		{
 			{"graph_symbol_net",
diff --git a/src/linux/btop_collect.cpp b/src/linux/btop_collect.cpp
index 595404d..4c82fef 100644
--- a/src/linux/btop_collect.cpp
+++ b/src/linux/btop_collect.cpp
@@ -732,6 +732,7 @@ namespace Mem {
 	fs::file_time_type fstab_time;
 	int disk_ios = 0;
 	vector<string> last_found;
+	const std::regex zfs_size_regex("^size\\s+\\d\\s+(\\d+)");
 
 	mem_info current_mem {};
 
@@ -754,11 +755,28 @@ namespace Mem {
 		auto& show_swap = Config::getB("show_swap");
 		auto& swap_disk = Config::getB("swap_disk");
 		auto& show_disks = Config::getB("show_disks");
+		auto& zfs_arc_cached = Config::getB("zfs_arc_cached");
 		auto totalMem = get_totalMem();
 		auto& mem = current_mem;
 
 		mem.stats.at("swap_total") = 0;
 
+		//? Read ZFS ARC info from /proc/spl/kstat/zfs/arcstats
+		uint64_t arc_size = 0;
+		if (zfs_arc_cached) {
+			ifstream arcstats(Shared::procPath / "spl/kstat/zfs/arcstats");
+			if (arcstats.good()) {
+				std::string line;
+				while (std::getline(arcstats, line)) {
+					std::smatch match;
+					if (std::regex_match(line, match, zfs_size_regex) && match.size() == 2) {
+						arc_size = stoull(match.str(1));
+					}
+				}
+			}
+			arcstats.close();
+		}
+
 		//? Read memory info from /proc/meminfo
 		ifstream meminfo(Shared::procPath / "meminfo");
 		if (meminfo.good()) {
@@ -790,6 +808,10 @@ namespace Mem {
 				meminfo.ignore(SSmax, '\n');
 			}
 			if (not got_avail) mem.stats.at("available") = mem.stats.at("free") + mem.stats.at("cached");
+			if (zfs_arc_cached) {
+				mem.stats.at("cached") += arc_size;
+				mem.stats.at("available") += arc_size;
+			}
 			mem.stats.at("used") = totalMem - mem.stats.at("available");
 			if (mem.stats.at("swap_total") > 0) mem.stats.at("swap_used") = mem.stats.at("swap_total") - mem.stats.at("swap_free");
 		}