bcache: New writeback PD controller
The old writeback PD controller could get into states where it had throttled all
the way down and take way too long to recover - it was too complicated to really
understand what it was doing.
This rewrites a good chunk of it to hopefully be simpler and make more sense,
and it also pays more attention to units which should make the behaviour a bit
easier to understand.
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index a7b1a76..754f4317 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -373,14 +373,14 @@
unsigned char writeback_percent;
unsigned writeback_delay;
- int writeback_rate_change;
- int64_t writeback_rate_derivative;
uint64_t writeback_rate_target;
+ int64_t writeback_rate_proportional;
+ int64_t writeback_rate_derivative;
+ int64_t writeback_rate_change;
unsigned writeback_rate_update_seconds;
unsigned writeback_rate_d_term;
unsigned writeback_rate_p_term_inverse;
- unsigned writeback_rate_d_smooth;
};
enum alloc_watermarks {