We no longer need carryover_[bytes/ios] in tg, so it is removed. The
related comments about carryover in tg are also merged into
[bytes/io]_disp, and modify other related comments.
Signed-off-by: Zizhi Wo <wozizhi@xxxxxxxxxx>
---
block/blk-throttle.c | 8 ++++----
block/blk-throttle.h | 19 ++++++++-----------
2 files changed, 12 insertions(+), 15 deletions(-)
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index df9825eb83be..4e4609dce85d 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -658,9 +658,9 @@ static void __tg_update_carryover(struct throtl_grp *tg, bool rw,
/*
* If config is updated while bios are still throttled, calculate and
- * accumulate how many bytes/ios are waited across changes. And
- * carryover_bytes/ios will be used to calculate new wait time under new
- * configuration.
+ * accumulate how many bytes/ios are waited across changes. And use the
+ * calculated carryover (@bytes/@ios) to update [bytes/io]_disp, which
+ * will be used to calculate new wait time under new configuration.
*/
if (bps_limit != U64_MAX) {
*bytes = calculate_bytes_allowed(bps_limit, jiffy_elapsed) -
@@ -687,7 +687,7 @@ static void tg_update_carryover(struct throtl_grp *tg)
__tg_update_carryover(tg, READ, &bytes[READ], &ios[READ]);
__tg_update_carryover(tg, WRITE, &bytes[WRITE], &ios[WRITE]);
- /* see comments in struct throtl_grp for meaning of these fields. */
+ /* see comments in struct throtl_grp for meaning of carryover. */
throtl_log(&tg->service_queue, "%s: %lld %lld %d %d\n", __func__,
bytes[READ], bytes[WRITE], ios[READ], ios[WRITE]);
}
diff --git a/block/blk-throttle.h b/block/blk-throttle.h
index 7964cc041e06..8bd16535302c 100644
--- a/block/blk-throttle.h
+++ b/block/blk-throttle.h
@@ -101,19 +101,16 @@ struct throtl_grp {
/* IOPS limits */
unsigned int iops[2];
- /* Number of bytes dispatched in current slice */
- int64_t bytes_disp[2];
- /* Number of bio's dispatched in current slice */
- int io_disp[2];
-
/*
- * The following two fields are updated when new configuration is
- * submitted while some bios are still throttled, they record how many
- * bytes/ios are waited already in previous configuration, and they will
- * be used to calculate wait time under new configuration.
+ * Number of bytes/bio's dispatched in current slice.
+ * When new configuration is submitted while some bios are still throttled,
+ * first calculate the carryover: the amount of bytes/IOs already waited
+ * under the previous configuration. Then, [bytes/io]_disp are represented
+ * as the negative of the carryover, and they will be used to calculate the
+ * wait time under the new configuration.
*/
- long long carryover_bytes[2];
- int carryover_ios[2];
+ int64_t bytes_disp[2];
+ int io_disp[2];
unsigned long last_check_time;
--
2.46.1
