diff options
Diffstat (limited to 'module')
| -rw-r--r-- | module/zfs/vdev.c | 86 |
1 files changed, 50 insertions, 36 deletions
diff --git a/module/zfs/vdev.c b/module/zfs/vdev.c index 64fc6fadd..50d230ccb 100644 --- a/module/zfs/vdev.c +++ b/module/zfs/vdev.c @@ -54,20 +54,20 @@ #include <sys/zvol.h> #include <sys/zfs_ratelimit.h> -/* target number of metaslabs per top-level vdev */ -int vdev_max_ms_count = 200; +/* default target for number of metaslabs per top-level vdev */ +int zfs_vdev_default_ms_count = 200; /* minimum number of metaslabs per top-level vdev */ -int vdev_min_ms_count = 16; +int zfs_vdev_min_ms_count = 16; /* practical upper limit of total metaslabs per top-level vdev */ -int vdev_ms_count_limit = 1ULL << 17; +int zfs_vdev_ms_count_limit = 1ULL << 17; /* lower limit for metaslab size (512M) */ -int vdev_default_ms_shift = 29; +int zfs_vdev_default_ms_shift = 29; -/* upper limit for metaslab size (256G) */ -int vdev_max_ms_shift = 38; +/* upper limit for metaslab size (16G) */ +int zfs_vdev_max_ms_shift = 34; int vdev_validate_skip = B_FALSE; @@ -2281,16 +2281,24 @@ void vdev_metaslab_set_size(vdev_t *vd) { uint64_t asize = vd->vdev_asize; - uint64_t ms_count = asize >> vdev_default_ms_shift; + uint64_t ms_count = asize >> zfs_vdev_default_ms_shift; uint64_t ms_shift; /* * There are two dimensions to the metaslab sizing calculation: * the size of the metaslab and the count of metaslabs per vdev. - * In general, we aim for vdev_max_ms_count (200) metaslabs. The - * range of the dimensions are as follows: * - * 2^29 <= ms_size <= 2^38 + * The default values used below are a good balance between memory + * usage (larger metaslab size means more memory needed for loaded + * metaslabs; more metaslabs means more memory needed for the + * metaslab_t structs), metaslab load time (larger metaslabs take + * longer to load), and metaslab sync time (more metaslabs means + * more time spent syncing all of them). + * + * In general, we aim for zfs_vdev_default_ms_count (200) metaslabs. + * The range of the dimensions are as follows: + * + * 2^29 <= ms_size <= 2^34 * 16 <= ms_count <= 131,072 * * On the lower end of vdev sizes, we aim for metaslabs sizes of @@ -2299,35 +2307,41 @@ vdev_metaslab_set_size(vdev_t *vd) * of at least 16 metaslabs will override this minimum size goal. * * On the upper end of vdev sizes, we aim for a maximum metaslab - * size of 256GB. However, we will cap the total count to 2^17 - * metaslabs to keep our memory footprint in check. + * size of 16GB. However, we will cap the total count to 2^17 + * metaslabs to keep our memory footprint in check and let the + * metaslab size grow from there if that limit is hit. * * The net effect of applying above constrains is summarized below. * - * vdev size metaslab count - * -------------|----------------- - * < 8GB ~16 - * 8GB - 100GB one per 512MB - * 100GB - 50TB ~200 - * 50TB - 32PB one per 256GB - * > 32PB ~131,072 - * ------------------------------- + * vdev size metaslab count + * --------------|----------------- + * < 8GB ~16 + * 8GB - 100GB one per 512MB + * 100GB - 3TB ~200 + * 3TB - 2PB one per 16GB + * > 2PB ~131,072 + * -------------------------------- + * + * Finally, note that all of the above calculate the initial + * number of metaslabs. Expanding a top-level vdev will result + * in additional metaslabs being allocated making it possible + * to exceed the zfs_vdev_ms_count_limit. */ - if (ms_count < vdev_min_ms_count) - ms_shift = highbit64(asize / vdev_min_ms_count); - else if (ms_count > vdev_max_ms_count) - ms_shift = highbit64(asize / vdev_max_ms_count); + if (ms_count < zfs_vdev_min_ms_count) + ms_shift = highbit64(asize / zfs_vdev_min_ms_count); + else if (ms_count > zfs_vdev_default_ms_count) + ms_shift = highbit64(asize / zfs_vdev_default_ms_count); else - ms_shift = vdev_default_ms_shift; + ms_shift = zfs_vdev_default_ms_shift; if (ms_shift < SPA_MAXBLOCKSHIFT) { ms_shift = SPA_MAXBLOCKSHIFT; - } else if (ms_shift > vdev_max_ms_shift) { - ms_shift = vdev_max_ms_shift; + } else if (ms_shift > zfs_vdev_max_ms_shift) { + ms_shift = zfs_vdev_max_ms_shift; /* cap the total count to constrain memory footprint */ - if ((asize >> ms_shift) > vdev_ms_count_limit) - ms_shift = highbit64(asize / vdev_ms_count_limit); + if ((asize >> ms_shift) > zfs_vdev_ms_count_limit) + ms_shift = highbit64(asize / zfs_vdev_ms_count_limit); } vd->vdev_ms_shift = ms_shift; @@ -4674,16 +4688,16 @@ EXPORT_SYMBOL(vdev_online); EXPORT_SYMBOL(vdev_offline); EXPORT_SYMBOL(vdev_clear); /* BEGIN CSTYLED */ -module_param(vdev_max_ms_count, int, 0644); -MODULE_PARM_DESC(vdev_max_ms_count, +module_param(zfs_vdev_default_ms_count, int, 0644); +MODULE_PARM_DESC(zfs_vdev_default_ms_count, "Target number of metaslabs per top-level vdev"); -module_param(vdev_min_ms_count, int, 0644); -MODULE_PARM_DESC(vdev_min_ms_count, +module_param(zfs_vdev_min_ms_count, int, 0644); +MODULE_PARM_DESC(zfs_vdev_min_ms_count, "Minimum number of metaslabs per top-level vdev"); -module_param(vdev_ms_count_limit, int, 0644); -MODULE_PARM_DESC(vdev_ms_count_limit, +module_param(zfs_vdev_ms_count_limit, int, 0644); +MODULE_PARM_DESC(zfs_vdev_ms_count_limit, "Practical upper limit of total metaslabs per top-level vdev"); module_param(zfs_slow_io_events_per_second, uint, 0644); |