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Subject: Re: [PATCH] blk-iocost: Fix systemtap error on iocost_ioc_vrate_adj
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Jens Axboe <axboe@kernel.dk>, Ingo Molnar <mingo@redhat.com>,
        Tejun Heo <tj@kernel.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        Ming Lei <ming.lei@redhat.com>
References: <20200421130755.18370-1-longman@redhat.com>
 <20200421105948.4f5a36f5@gandalf.local.home>
From:   Waiman Long <longman@redhat.com>
Organization: Red Hat
Message-ID: <22ccb042-7d6f-3717-4024-9ec094b2f363@redhat.com>
Date:   Tue, 21 Apr 2020 14:36:29 -0400
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On 4/21/20 10:59 AM, Steven Rostedt wrote:
> On Tue, 21 Apr 2020 09:07:55 -0400
> Waiman Long <longman@redhat.com> wrote:
>
>> diff --git a/include/trace/events/iocost.h b/include/trace/events/iocost.h
>> index 7ecaa65b7106..c2f580fd371b 100644
>> --- a/include/trace/events/iocost.h
>> +++ b/include/trace/events/iocost.h
>> @@ -130,7 +130,7 @@ DEFINE_EVENT(iocg_inuse_update, iocost_inuse_reset,
>>  
>>  TRACE_EVENT(iocost_ioc_vrate_adj,
>>  
>> -	TP_PROTO(struct ioc *ioc, u64 new_vrate, u32 (*missed_ppm)[2],
>> +	TP_PROTO(struct ioc *ioc, u64 new_vrate, u32 *missed_ppm,
>>  		u32 rq_wait_pct, int nr_lagging, int nr_shortages,
>>  		int nr_surpluses),
>>  
>> @@ -155,8 +155,8 @@ TRACE_EVENT(iocost_ioc_vrate_adj,
>>  		__entry->old_vrate = atomic64_read(&ioc->vtime_rate);;
>>  		__entry->new_vrate = new_vrate;
>>  		__entry->busy_level = ioc->busy_level;
>> -		__entry->read_missed_ppm = (*missed_ppm)[READ];
>> -		__entry->write_missed_ppm = (*missed_ppm)[WRITE];
>> +		__entry->read_missed_ppm = missed_ppm[READ];
>> +		__entry->write_missed_ppm = missed_ppm[WRITE];
>>  		__entry->rq_wait_pct = rq_wait_pct;
>>  		__entry->nr_lagging = nr_lagging;
>>  		__entry->nr_shortages = nr_shortages;
> Regardless if this helps systemtap or not, I like the patch because the
> current code is rather ugly, and this patch makes it more readable.
>
> Suggestion: change the topic to remove systemtap, as that's not going to be
> the true reason for acceptance of this patch. It should just be about
> cleaning up the trace event itself.
>
> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
>
> -- Steve
>
OK, will send a v2 patch to update the commit log. Thanks for the review.

Cheers,
Longman