Searched hist:"91 be66e1318f67ed5888ca10e10cc8ffdc24f661" (Results 1 – 2 of 2) sorted by relevance
| /linux/drivers/md/bcache/ |
| H A D | journal.h | diff 91be66e1318f67ed5888ca10e10cc8ffdc24f661 Fri Jun 28 13:59:59 CEST 2019 Coly Li <colyli@suse.de> bcache: performance improvement for btree_flush_write()
This patch improves performance for btree_flush_write() in following
ways,
- Use another spinlock journal.flush_write_lock to replace the very
hot journal.lock. We don't have to use journal.lock here, selecting
candidate btree nodes takes a lot of time, hold journal.lock here will
block other jouranling threads and drop the overall I/O performance.
- Only select flushing btree node from c->btree_cache list. When the
machine has a large system memory, mca cache may have a huge number of
cached btree nodes. Iterating all the cached nodes will take a lot
of CPU time, and most of the nodes on c->btree_cache_freeable and
c->btree_cache_freed lists are cleared and have need to flush. So only
travel mca list c->btree_cache to select flushing btree node should be
enough for most of the cases.
- Don't iterate whole c->btree_cache list, only reversely select first
BTREE_FLUSH_NR btree nodes to flush. Iterate all btree nodes from
c->btree_cache and select the oldest journal pin btree nodes consumes
huge number of CPU cycles if the list is huge (push and pop a node
into/out of a heap is expensive). The last several dirty btree nodes
on the tail of c->btree_cache list are earlest allocated and cached
btree nodes, they are relative to the oldest journal pin btree nodes.
Therefore only flushing BTREE_FLUSH_NR btree nodes from tail of
c->btree_cache probably includes the oldest journal pin btree nodes.
In my testing, the above change decreases 50%+ CPU consumption when
journal space is full. Some times IOPS drops to 0 for 5-8 seconds,
comparing blocking I/O for 120+ seconds in previous code, this is much
better. Maybe there is room to improve in future, but at this momment
the fix looks fine and performs well in my testing.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
| H A D | journal.c | diff 91be66e1318f67ed5888ca10e10cc8ffdc24f661 Fri Jun 28 13:59:59 CEST 2019 Coly Li <colyli@suse.de> bcache: performance improvement for btree_flush_write()
This patch improves performance for btree_flush_write() in following
ways,
- Use another spinlock journal.flush_write_lock to replace the very
hot journal.lock. We don't have to use journal.lock here, selecting
candidate btree nodes takes a lot of time, hold journal.lock here will
block other jouranling threads and drop the overall I/O performance.
- Only select flushing btree node from c->btree_cache list. When the
machine has a large system memory, mca cache may have a huge number of
cached btree nodes. Iterating all the cached nodes will take a lot
of CPU time, and most of the nodes on c->btree_cache_freeable and
c->btree_cache_freed lists are cleared and have need to flush. So only
travel mca list c->btree_cache to select flushing btree node should be
enough for most of the cases.
- Don't iterate whole c->btree_cache list, only reversely select first
BTREE_FLUSH_NR btree nodes to flush. Iterate all btree nodes from
c->btree_cache and select the oldest journal pin btree nodes consumes
huge number of CPU cycles if the list is huge (push and pop a node
into/out of a heap is expensive). The last several dirty btree nodes
on the tail of c->btree_cache list are earlest allocated and cached
btree nodes, they are relative to the oldest journal pin btree nodes.
Therefore only flushing BTREE_FLUSH_NR btree nodes from tail of
c->btree_cache probably includes the oldest journal pin btree nodes.
In my testing, the above change decreases 50%+ CPU consumption when
journal space is full. Some times IOPS drops to 0 for 5-8 seconds,
comparing blocking I/O for 120+ seconds in previous code, this is much
better. Maybe there is room to improve in future, but at this momment
the fix looks fine and performs well in my testing.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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