Decrease contention on dn_struct_rwlock

Currently, sequential async write workloads spend a lot of time 
contending on the dn_struct_rwlock. This lock is responsible for 
protecting the entire block tree below it; this naturally results 
in some serialization during heavy write workloads. This can be 
resolved by having per-dbuf locking, which will allow multiple 
writers in the same object at the same time.

We introduce a new rwlock, the db_rwlock. This lock is responsible 
for protecting the contents of the dbuf that it is a part of; when 
reading a block pointer from a dbuf, you hold the lock as a reader. 
When writing data to a dbuf, you hold it as a writer. This allows 
multiple threads to write to different parts of a file at the same 
time.

Reviewed by: Brad Lewis <[email protected]>
Reviewed by: Matt Ahrens [email protected]
Reviewed by: George Wilson [email protected]
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Paul Dagnelie <[email protected]>
External-issue: DLPX-52564
External-issue: DLPX-53085
External-issue: DLPX-57384
Closes #8946

0 files changed, 0 insertions, 0 deletions