diff options
| -rw-r--r-- | man/man5/zfs-module-parameters.5 | 13 | ||||
| -rw-r--r-- | module/zfs/vdev.c | 82 |
2 files changed, 67 insertions, 28 deletions
diff --git a/man/man5/zfs-module-parameters.5 b/man/man5/zfs-module-parameters.5 index 41be2d8ba..a2c32db8d 100644 --- a/man/man5/zfs-module-parameters.5 +++ b/man/man5/zfs-module-parameters.5 @@ -296,7 +296,7 @@ Use \fB1\fR for yes (default) and \fB0\fR for no. \fBvdev_max_ms_count\fR (int) .ad .RS 12n -When a vdev is added, it will be divided into approximately (but no more than) this number of metaslabs. +When a vdev is added target this number of metaslabs per top-level vdev. .sp Default value: \fB200\fR. .RE @@ -315,6 +315,17 @@ Default value: \fB16\fR. .sp .ne 2 .na +\fBvdev_ms_count_limit\fR (int) +.ad +.RS 12n +Practical upper limit of total metaslabs per top-level vdev. +.sp +Default value: \fB131,072\fR. +.RE + +.sp +.ne 2 +.na \fBmetaslab_preload_enabled\fR (int) .ad .RS 12n diff --git a/module/zfs/vdev.c b/module/zfs/vdev.c index 6db6fbacb..ef6e2d8be 100644 --- a/module/zfs/vdev.c +++ b/module/zfs/vdev.c @@ -52,15 +52,21 @@ #include <sys/zvol.h> #include <sys/zfs_ratelimit.h> -/* maximum number of metaslabs per top-level vdev */ +/* target number of metaslabs per top-level vdev */ int vdev_max_ms_count = 200; -/* minimum amount of metaslabs per top-level vdev */ +/* minimum number of metaslabs per top-level vdev */ int vdev_min_ms_count = 16; -/* see comment in vdev_metaslab_set_size() */ +/* practical upper limit of total metaslabs per top-level vdev */ +int vdev_ms_count_limit = 1ULL << 17; + +/* lower limit for metaslab size (512M) */ int vdev_default_ms_shift = 29; +/* upper limit for metaslab size (256G) */ +int vdev_max_ms_shift = 38; + int vdev_validate_skip = B_FALSE; /* @@ -2130,34 +2136,53 @@ void vdev_metaslab_set_size(vdev_t *vd) { uint64_t asize = vd->vdev_asize; - uint64_t ms_shift = 0; + uint64_t ms_count = asize >> vdev_default_ms_shift; + uint64_t ms_shift; /* - * For vdevs that are bigger than 8G the metaslab size varies in - * a way that the number of metaslabs increases in powers of two, - * linearly in terms of vdev_asize, starting from 16 metaslabs. - * So for vdev_asize of 8G we get 16 metaslabs, for 16G, we get 32, - * and so on, until we hit the maximum metaslab count limit - * [vdev_max_ms_count] from which point the metaslab count stays - * the same. + * 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 + * 16 <= ms_count <= 131,072 + * + * On the lower end of vdev sizes, we aim for metaslabs sizes of + * at least 512MB (2^29) to minimize fragmentation effects when + * testing with smaller devices. However, the count constraint + * 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. + * + * 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 + * ------------------------------- */ - ms_shift = vdev_default_ms_shift; - if ((asize >> ms_shift) < vdev_min_ms_count) { - /* - * For devices that are less than 8G we want to have - * exactly 16 metaslabs. We don't want less as integer - * division rounds down, so less metaslabs mean more - * wasted space. We don't want more as these vdevs are - * small and in the likely event that we are running - * out of space, the SPA will have a hard time finding - * space due to fragmentation. - */ + if (ms_count < vdev_min_ms_count) ms_shift = highbit64(asize / vdev_min_ms_count); - ms_shift = MAX(ms_shift, SPA_MAXBLOCKSHIFT); - - } else if ((asize >> ms_shift) > vdev_max_ms_count) { + else if (ms_count > vdev_max_ms_count) ms_shift = highbit64(asize / vdev_max_ms_count); + else + ms_shift = 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; + /* cap the total count to constrain memory footprint */ + if ((asize >> ms_shift) > vdev_ms_count_limit) + ms_shift = highbit64(asize / vdev_ms_count_limit); } vd->vdev_ms_shift = ms_shift; @@ -4392,13 +4417,16 @@ EXPORT_SYMBOL(vdev_clear); /* BEGIN CSTYLED */ module_param(vdev_max_ms_count, int, 0644); MODULE_PARM_DESC(vdev_max_ms_count, - "Divide added vdev into approximately (but no more than) this number " - "of metaslabs"); + "Target number of metaslabs per top-level vdev"); module_param(vdev_min_ms_count, int, 0644); MODULE_PARM_DESC(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, + "Practical upper limit of total metaslabs per top-level vdev"); + module_param(zfs_delays_per_second, uint, 0644); MODULE_PARM_DESC(zfs_delays_per_second, "Rate limit delay events to this many " "IO delays per second"); |