From bc25c9325b0e5ced897b9820dad239539d561ec9 Mon Sep 17 00:00:00 2001 From: Chunwei Chen Date: Tue, 13 May 2014 10:36:35 +0800 Subject: [PATCH] Use a dedicated taskq for vdev_file Originally, vdev_file used system_taskq. This would cause a deadlock, especially on system with few CPUs. The reason is that the prefetcher threads, which are on system_taskq, will sometimes be blocked waiting for I/O to finish. If the prefetcher threads consume all the tasks in system_taskq, the I/O cannot be served and thus results in a deadlock. We fix this by creating a dedicated vdev_file_taskq for vdev_file I/O. Signed-off-by: Chunwei Chen Signed-off-by: Brian Behlendorf Closes #2270 --- include/sys/vdev_file.h | 3 +++ module/zfs/spa_misc.c | 3 +++ module/zfs/vdev_file.c | 19 ++++++++++++++++++- 3 files changed, 24 insertions(+), 1 deletion(-) diff --git a/include/sys/vdev_file.h b/include/sys/vdev_file.h index b4d40f9df..cf38a86af 100644 --- a/include/sys/vdev_file.h +++ b/include/sys/vdev_file.h @@ -39,6 +39,9 @@ typedef struct vdev_file { vnode_t *vf_vnode; } vdev_file_t; +extern void vdev_file_init(void); +extern void vdev_file_fini(void); + #ifdef __cplusplus } #endif diff --git a/module/zfs/spa_misc.c b/module/zfs/spa_misc.c index cdbe5a522..935a61796 100644 --- a/module/zfs/spa_misc.c +++ b/module/zfs/spa_misc.c @@ -34,6 +34,7 @@ #include #include #include +#include #include #include #include @@ -1660,6 +1661,7 @@ spa_init(int mode) dmu_init(); zil_init(); vdev_cache_stat_init(); + vdev_file_init(); zfs_prop_init(); zpool_prop_init(); zpool_feature_init(); @@ -1674,6 +1676,7 @@ spa_fini(void) spa_evict_all(); + vdev_file_fini(); vdev_cache_stat_fini(); zil_fini(); dmu_fini(); diff --git a/module/zfs/vdev_file.c b/module/zfs/vdev_file.c index 858582aca..330580224 100644 --- a/module/zfs/vdev_file.c +++ b/module/zfs/vdev_file.c @@ -36,6 +36,8 @@ * Virtual device vector for files. */ +static taskq_t *vdev_file_taskq; + static void vdev_file_hold(vdev_t *vd) { @@ -184,7 +186,7 @@ vdev_file_io_start(zio_t *zio) return (ZIO_PIPELINE_CONTINUE); } - VERIFY3U(taskq_dispatch(system_taskq, vdev_file_io_strategy, zio, + VERIFY3U(taskq_dispatch(vdev_file_taskq, vdev_file_io_strategy, zio, TQ_PUSHPAGE), !=, 0); return (ZIO_PIPELINE_STOP); @@ -209,6 +211,21 @@ vdev_ops_t vdev_file_ops = { B_TRUE /* leaf vdev */ }; +void +vdev_file_init(void) +{ + vdev_file_taskq = taskq_create("vdev_file_taskq", 100, minclsyspri, + max_ncpus, INT_MAX, TASKQ_PREPOPULATE | TASKQ_THREADS_CPU_PCT); + + VERIFY(vdev_file_taskq); +} + +void +vdev_file_fini(void) +{ + taskq_destroy(vdev_file_taskq); +} + /* * From userland we access disks just like files. */ -- 2.40.0