Bug #54
metaslab_min_alloc_size may be too big
| Status: | Closed | Start date: | 2010-08-18 | |
|---|---|---|---|---|
| Priority: | Normal | Due date: | ||
| Assignee: | - | % Done: | 0% |
|
| Category: | - | Spent time: | - | |
| Target version: | - | |||
| Difficulty: | Medium | Tags: | needs-triage |
Description
See bugs.opensolaris.org: CR 6962304. It seems like we could adjust this tunable to be a bit more sane.
The current default value of metaslab_min_alloc_size is 10M
Several systems which have pools that are in the neighborhood of 70% or so full
were observed spending a lot of time in metaslab-related code and were generally seen as slow.
Someone suggested patching metaslab_min_alloc_size to 4K, and this has significantly reduced the amount of cpu used by zfs and made the systems significantly more responsive.
Looks like the default value is wrong.
Workaround:
Add the following to /etc/system and reboot:
- Work around 6962304
set zfs:metaslab_min_alloc_size=0x1000
History
Updated by Garrett D'Amore over 2 years ago
- Status changed from New to Closed
- Difficulty set to Medium
- Tags set to needs-triage
Turns out this tunable is made irrelevant as a result of a change to use the metaslab_df_ops allocator. We don't need to change it. I'm closing this bug.