From: Namhyung Kim <namhyung@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Namhyung Kim <namhyung.kim@lge.com>, Jens Axboe <axboe@kernel.dk>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] block: prevent duplicated bio completion report
Date: Wed, 18 Jan 2012 10:20:03 +0900 [thread overview]
Message-ID: <4F161E43.5040705@gmail.com> (raw)
In-Reply-To: <20120117174520.GB6762@google.com>
Hi,
2012-01-18 2:45 AM, Tejun Heo wrote:
> Hello,
>
> On Tue, Jan 17, 2012 at 10:32:07AM +0900, Namhyung Kim wrote:
>> Since previous patch make block_bio_complete TP working,
>> it will generate duplicated BLK_TA_COMPLETEs for bounced
>> bios. Fix it.
>>
>> Signed-off-by: Namhyung Kim <namhyung.kim@lge.com>
>> Cc: Tejun Heo <tj@kernel.org>
>
> This and the third patch should probably be merged to the first patch.
> As it currently stands, it introduces window where spurious events are
> generated.
OK, will do.
>
>> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
>> index 4053cbd4490e..45cd0074a1c8 100644
>> --- a/include/linux/blk_types.h
>> +++ b/include/linux/blk_types.h
>> @@ -97,6 +97,9 @@ struct bio {
>> #define BIO_MAPPED_INTEGRITY 11/* integrity metadata has been remapped */
>> #define bio_flagged(bio, flag) ((bio)->bi_flags& (1<< (flag)))
>>
>> +/* masked bio's won't report its completion via tracepoint */
>> +#define BIO_COMPLETE_MASK (1<< BIO_BOUNCED)
>
> And, who's setting this flag?
__blk_queue_bounce() does.
>
>> /*
>> * top 4 bits of bio flags indicate the pool this bio came from
>> */
>> diff --git a/include/trace/events/block.h b/include/trace/events/block.h
>> index 96955f4828b3..72888542e186 100644
>> --- a/include/trace/events/block.h
>> +++ b/include/trace/events/block.h
>> @@ -219,7 +219,8 @@ TRACE_EVENT_CONDITION(block_bio_complete,
>>
>> TP_ARGS(q, bio, error),
>>
>> - TP_CONDITION(bio->bi_bdev != NULL),
>> + TP_CONDITION(bio->bi_bdev != NULL&&
>> + !(bio->bi_flags& BIO_COMPLETE_MASK)),
>
> Bounced bio's are separate bio's too and I don't think masking its
> completion from the TP itself is a good idea. As I wrote before, why
> not do this from blktrace code?
Because blktrace cannot know about the bi_flags, as I said before. :)
And although the bounced bio's are separate ones, they aren't queued
separately. They just get replaced on the way.
Besides, I think accounting wait_time of them will result in an invalid
value unless it's handled somehow in block_bio_bounce and/or
block_rq_issue TP.
Thanks,
Namhyung
next prev parent reply other threads:[~2012-01-18 1:20 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-17 1:32 [PATCH 1/3] block: add missing block_bio_complete() tracepoint Namhyung Kim
2012-01-17 1:32 ` [PATCH 2/3] block: prevent duplicated bio completion report Namhyung Kim
2012-01-17 17:45 ` Tejun Heo
2012-01-18 1:20 ` Namhyung Kim [this message]
2012-01-19 1:14 ` Namhyung Kim
2012-01-17 1:32 ` [PATCH 3/3] block: don't export block_bio_complete tracepoint Namhyung Kim
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