git: 1c090bf880bf - stable/14 - top: Avoid printing a blank line when the ZFS ARC is empty

The branch stable/14 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=1c090bf880bf8879f75e4cd4b93c9a277faef2fa

commit 1c090bf880bf8879f75e4cd4b93c9a277faef2fa
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2024-01-11 14:58:31 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2024-01-25 14:57:12 +0000

    top: Avoid printing a blank line when the ZFS ARC is empty
    
    PR:             275994
    MFC after:      2 weeks
    
    (cherry picked from commit 1f62718d8ba26d813d8c2e826ac5f4caee4c6730)
---
 usr.bin/top/machine.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/usr.bin/top/machine.c b/usr.bin/top/machine.c
index b4cd29dab878..a76d77a80ce4 100644
--- a/usr.bin/top/machine.c
+++ b/usr.bin/top/machine.c
@@ -293,17 +293,27 @@ machine_init(struct statics *statics)
 	size = sizeof(carc_en);
 	if (arc_enabled &&
 	    sysctlbyname("vfs.zfs.compressed_arc_enabled", &carc_en, &size,
-	    NULL, 0) == 0 && carc_en == 1)
-		carc_enabled = 1;
+	    NULL, 0) == 0 && carc_en == 1) {
+		uint64_t uncomp_sz;
+
+		/*
+		 * Don't report compression stats if no data is in the ARC.
+		 * Otherwise, we end up printing a blank line.
+		 */
+		size = sizeof(uncomp_sz);
+		if (sysctlbyname("kstat.zfs.misc.arcstats.uncompressed_size",
+		    &uncomp_sz, &size, NULL, 0) == 0 && uncomp_sz != 0)
+			carc_enabled = 1;
+	}
 
 	kd = kvm_open(NULL, _PATH_DEVNULL, NULL, O_RDONLY, "kvm_open");
 	if (kd == NULL)
 		return (-1);
 
 	size = sizeof(nswapdev);
-	if (sysctlbyname("vm.nswapdev", &nswapdev, &size, NULL,
-		0) == 0 && nswapdev != 0)
-			has_swap = 1;
+	if (sysctlbyname("vm.nswapdev", &nswapdev, &size, NULL, 0) == 0 &&
+	    nswapdev != 0)
+		has_swap = 1;
 
 	GETSYSCTL("kern.ccpu", ccpu);