drbd: new configuration parameter c-min-rate

We now track the data rate of locally submitted resync related requests,
and can thus detect non-resync activity on the lower level device.

If the current sync rate is above c-min-rate, and the lower level device
appears to be busy, we throttle the resyncer.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

2 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/drbd_limits.h b/include/linux/drbd_limits.h
index 06dbba47a8ef..0b24ded6fffd 100644
--- a/include/linux/drbd_limits.h
+++ b/include/linux/drbd_limits.h
@@ -150,5 +150,9 @@
 #define DRBD_C_MAX_RATE_MAX     (4 << 20)
 #define DRBD_C_MAX_RATE_DEF     102400
 
+#define DRBD_C_MIN_RATE_MIN     0 /* kByte/sec */
+#define DRBD_C_MIN_RATE_MAX     (4 << 20)
+#define DRBD_C_MIN_RATE_DEF     4096
+
 #undef RANGE
 #endif
diff --git a/include/linux/drbd_nl.h b/include/linux/drbd_nl.h
index e23683c87ca1..ade91107c9a5 100644
--- a/include/linux/drbd_nl.h
+++ b/include/linux/drbd_nl.h
@@ -92,6 +92,7 @@ NL_PACKET(syncer_conf, 8,
         NL_INTEGER(     77,     T_MAY_IGNORE,   c_delay_target)
         NL_INTEGER(     78,     T_MAY_IGNORE,   c_fill_target)
         NL_INTEGER(     79,     T_MAY_IGNORE,   c_max_rate)
+        NL_INTEGER(     80,     T_MAY_IGNORE,   c_min_rate)
 )
 
 NL_PACKET(invalidate, 9, )