linux-kernel - Re: [PATCH] block/bfq: fix ifdef for CONFIG_BFQ_GROUP

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Date:   Fri, 29 Mar 2019 09:58:22 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Holger Hoffstätte <holger@...lied-asynchrony.com>,
        Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
        linux-block@...r.kernel.org,
        Paolo Valente <paolo.valente@...aro.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] block/bfq: fix ifdef for CONFIG_BFQ_GROUP_IOSCHED=y

On 3/29/19 9:56 AM, Holger Hoffstätte wrote:
> On 3/29/19 3:01 PM, Konstantin Khlebnikov wrote:
>> Replace BFQ_GROUP_IOSCHED_ENABLED with CONFIG_BFQ_GROUP_IOSCHED.
>> Code under these ifdefs never worked, something might be broken.
>>
>> Fixes: 0471559c2fbd ("block, bfq: add/remove entity weights correctly")
>> Fixes: 73d58118498b ("block, bfq: consider also ioprio classes in symmetry detection")
>> Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
>> ---
>>   block/bfq-iosched.c |    2 +-
>>   block/bfq-wf2q.c    |    2 +-
>>   2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
>> index 4c592496a16a..fac188dd78fa 100644
>> --- a/block/bfq-iosched.c
>> +++ b/block/bfq-iosched.c
>> @@ -674,7 +674,7 @@ static bool bfq_symmetric_scenario(struct bfq_data *bfqd)
>>   	 * at least two nodes.
>>   	 */
>>   	return !(varied_queue_weights || multiple_classes_busy
>> -#ifdef BFQ_GROUP_IOSCHED_ENABLED
>> +#ifdef CONFIG_BFQ_GROUP_IOSCHED
>>   	       || bfqd->num_groups_with_pending_reqs > 0
>>   #endif
>>   		);
>> diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
>> index 63311d1ff1ed..a11bef75483d 100644
>> --- a/block/bfq-wf2q.c
>> +++ b/block/bfq-wf2q.c
>> @@ -1012,7 +1012,7 @@ static void __bfq_activate_entity(struct bfq_entity *entity,
>>   		entity->on_st = true;
>>   	}
>>   
>> -#ifdef BFQ_GROUP_IOSCHED_ENABLED
>> +#ifdef CONFIG_BFQ_GROUP_IOSCHED
>>   	if (!bfq_entity_to_bfqq(entity)) { /* bfq_group */
>>   		struct bfq_group *bfqg =
>>   			container_of(entity, struct bfq_group, entity);
>>
>>
> 
> Good catch! I run without group scheduling and therefore didn't notice these
> stray defines earlier. For 5.1 it should merge cleanly; adding this on top of
> the pending 5.2 BFQ patches required a small context fixup in hunk #1 due to
> "block, bfq: do not idle for lowest-weight queues".

I'm hesitant to apply this, since the group scheduling stuff has obviously never
been tested.

Hence it should go through some actual testing first, which means it's a 5.2
candidate, not 5.1.

-- 
Jens Axboe