FreeBSD: reduce priority of ZIO_TASKQ_ISSUE writes by a larger value

On FreeBSD, if priorities divided by four (RQ_PPQ) are equal then a difference between them is insignificant. In other words, incrementing pri by only one as on Linux is insufficient. Reviewed-by: Alexander Motin <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Matt Macy <[email protected]> Closes openzfs#10872
jsai20 · Mar 30, 2021 · 6189bef · 6189bef
1 parent 3fae1b4
commit 6189bef
Showing 1 changed file with 17 additions and 5 deletions.
diff --git a/module/zfs/spa.c b/module/zfs/spa.c
@@ -1000,13 +1000,25 @@ spa_taskqs_init(spa_t *spa, zio_type_t t, zio_taskq_type_t q)
 			/*
 			 * The write issue taskq can be extremely CPU
 			 * intensive.  Run it at slightly less important
-			 * priority than the other taskqs.  Under Linux this
-			 * means incrementing the priority value on platforms
-			 * like illumos it should be decremented.
+			 * priority than the other taskqs.
+			 *
+			 * Under Linux and FreeBSD this means incrementing
+			 * the priority value as opposed to platforms like
+			 * illumos where it should be decremented.
+			 *
+			 * On FreeBSD, if priorities divided by four (RQ_PPQ)
+			 * are equal then a difference between them is
+			 * insignificant.
 			 */
-			if (t == ZIO_TYPE_WRITE && q == ZIO_TASKQ_ISSUE)
+			if (t == ZIO_TYPE_WRITE && q == ZIO_TASKQ_ISSUE) {
+#if defined(__linux__)
 				pri++;
-
+#elif defined(__FreeBSD__)
+				pri += 4;
+#else
+#error "unknown OS"
+#endif
+			}
 			tq = taskq_create_proc(name, value, pri, 50,
 			    INT_MAX, spa->spa_proc, flags);
 		}