linux-kernel - [PATCH V2 1/1] block,bfq: Disable writeback throttling

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Message-Id: <20171009142721.4262-2-lucmiccio@gmail.com>
Date:   Mon,  9 Oct 2017 16:27:21 +0200
From:   Luca Miccio <lucmiccio@...il.com>
To:     axboe@...nel.dk
Cc:     paolo.valente@...aro.org, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH V2 1/1] block,bfq: Disable writeback throttling

Similarly to CFQ, BFQ has its write-throttling heuristics, and it
is better not to combine them with further write-throttling
heuristics of a different nature.
So this commit disables write-back throttling for a device if BFQ
is used as I/O scheduler for that device.

Signed-off-by: Luca Miccio <lucmiccio@...il.com>
Signed-off-by: Paolo Valente <paolo.valente@...aro.org>
Tested-by: Oleksandr Natalenko <oleksandr@...alenko.name>
Tested-by: Lee Tibbert <lee.tibbert@...il.com>
---
 block/bfq-iosched.c | 3 ++-
 block/blk-wbt.c     | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index a4783da90ba8..0f860cf0d56d 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -108,6 +108,7 @@
 #include "blk-mq-tag.h"
 #include "blk-mq-sched.h"
 #include "bfq-iosched.h"
+#include "blk-wbt.h"
 
 #define BFQ_BFQQ_FNS(name)						\
 void bfq_mark_bfqq_##name(struct bfq_queue *bfqq)			\
@@ -4775,7 +4776,7 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
 	bfq_init_root_group(bfqd->root_group, bfqd);
 	bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group);
 
-
+	wbt_disable_default(q);
 	return 0;
 
 out_free:
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 6a9a0f03a67b..e59d59c11ebb 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -654,7 +654,7 @@ void wbt_set_write_cache(struct rq_wb *rwb, bool write_cache_on)
 }
 
 /*
- * Disable wbt, if enabled by default. Only called from CFQ.
+ * Disable wbt, if enabled by default.
  */
 void wbt_disable_default(struct request_queue *q)
 {
-- 
2.11.0