Make zvol io taskq thread number configurable

Author: arun-kv

include/os/windows/zfs/sys/kstat_windows.h

@@ -149,6 +149,7 @@ typedef struct windows_kstat {
 	kstat_named_t zfs_total_memory_limit;
 	kstat_named_t zfs_removal_suspend_progress;
 	kstat_named_t cpu_avx_supported;
+	kstat_named_t zvol_io_threads;
 } windows_kstat_t;
 
 
@@ -259,6 +260,7 @@ extern uint64_t zfs_initialize_value;
 extern int zfs_autoimport_disable;
 extern int zfs_removal_suspend_progress;
 extern int cpu_avx_supported;
+extern int zvol_io_threads;
 
 int  kstat_windows_init(void *);
 void kstat_windows_fini(void);

module/os/windows/zfs/arc_os.c

@@ -695,6 +695,8 @@ arc_kstat_update_windows(kstat_t *ksp, int rw)
 		zfs_arc_p_min_shift = ks->arc_zfs_arc_p_min_shift.value.ui64;
 		zfs_arc_average_blocksize =
 		    ks->arc_zfs_arc_average_blocksize.value.ui64;
+		zvol_io_threads =
+		    ks->zvol_io_threads.value.ui32;
 
 #ifdef _KERNEL
 		if (ks->zfs_total_memory_limit.value.ui64 > total_memory &&
@@ -729,6 +731,7 @@ arc_kstat_update_windows(kstat_t *ksp, int rw)
 		ks->arc_zfs_arc_p_min_shift.value.ui64 = zfs_arc_p_min_shift;
 		ks->arc_zfs_arc_average_blocksize.value.ui64 =
 		    zfs_arc_average_blocksize;
+		ks->zvol_io_threads.value.ui32 = zvol_io_threads;
 
 #ifdef _KERNEL
 		ks->zfs_total_memory_limit.value.ui64 = total_memory;

module/os/windows/zfs/zfs_kstat_windows.c

@@ -172,7 +172,8 @@ windows_kstat_t windows_kstat = {
 	{ "zfs_autoimport_disable",		KSTAT_DATA_UINT64 },
 	{ "zfs_total_memory_limit",		KSTAT_DATA_UINT64 },
 	{ "zfs_removal_suspend_progress",	KSTAT_DATA_INT32 },
-	{ "cpu_avx_supported",			KSTAT_DATA_UINT32 }
+	{ "cpu_avx_supported",			KSTAT_DATA_UINT32 },
+	{ "zvol_io_threads",			KSTAT_DATA_UINT32 }
 };
 
 
@@ -382,6 +383,8 @@ windows_kstat_update(kstat_t *ksp, int rw)
 		    ks->zfs_removal_suspend_progress.value.i32;
 		cpu_avx_supported =
 		    ks->cpu_avx_supported.value.ui32;
+		zvol_io_threads =
+		    ks->zvol_io_threads.value.ui32;
 
 	} else {
 
@@ -571,6 +574,8 @@ windows_kstat_update(kstat_t *ksp, int rw)
 		    zfs_removal_suspend_progress;
 		ks->cpu_avx_supported.value.ui32 =
 		    cpu_avx_supported;
+		ks->zvol_io_threads.value.ui32 =
+		    zvol_io_threads;
 	}
 	arc_kstat_update_windows(ksp, rw);
 	return (0);

module/os/windows/zfs/zvol_os.c

@@ -46,6 +46,7 @@ unsigned int zvol_request_sync = 0;
 unsigned int zvol_prefetch_bytes = (128 * 1024);
 unsigned long zvol_max_discard_blocks = 16384;
 unsigned int zvol_threads = 32;
+int zvol_io_threads = 0;
 
 taskq_t *zvol_taskq;
 
@@ -1028,8 +1029,15 @@ const static zvol_platform_ops_t zvol_windows_ops = {
 int
 zvol_init(void)
 {
+	if (!zvol_io_threads)
+		zvol_io_threads = zvol_threads;
+
+	zvol_threads = zvol_io_threads;
+
 	int threads = MIN(MAX(zvol_threads, 1), 1024);
 
+	KdPrintEx((DPFLTR_IHVDRIVER_ID, DPFLTR_ERROR_LEVEL,
+		"%s: zvol taskq threads %d regvalue: %d\n", __func__, threads, zvol_io_threads));
 	zvol_taskq = taskq_create(ZVOL_DRIVER, threads, maxclsyspri,
 	    threads * 2, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
 	if (zvol_taskq == NULL) {