lkml.org 
[lkml]   [2019]   [Jan]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH BUGFIX IMPROVEMENT 03/14] block, bfq: make sure queue budgets are not below service received
Date
With some unlucky sequences of events, the function
bfq_updated_next_req updates the current budget of a bfq_queue to a
lower value than the service received by the queue using such a
budget. Unfortunately, if this happens, then the return value of the
function bfq_bfqq_budget_left becomes inconsistent. This commit
solves this problem by lower-bounding the budget computed in
bfq_updated_next_req to the service currently charged to the queue.

Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
---
block/bfq-iosched.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 9ea2c4f42501..b0e8006475be 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -907,8 +907,10 @@ static void bfq_updated_next_req(struct bfq_data *bfqd,
*/
return;

- new_budget = max_t(unsigned long, bfqq->max_budget,
- bfq_serv_to_charge(next_rq, bfqq));
+ new_budget = max_t(unsigned long,
+ max_t(unsigned long, bfqq->max_budget,
+ bfq_serv_to_charge(next_rq, bfqq)),
+ entity->service);
if (entity->budget != new_budget) {
entity->budget = new_budget;
bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu",
--
2.20.1
\
 
 \ /
  Last update: 2019-01-29 12:07    [W:0.074 / U:28.576 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site