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From: Paolo Valente <paolo.valente@linaro.org>
To: Jens Axboe <axboe@fb.com>
Cc: Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org,
	Linux-Kernal <linux-kernel@vger.kernel.org>,
	Omar Sandoval <osandov@fb.com>,
	Linus Walleij <linus.walleij@linaro.org>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Mark Brown <broonie@kernel.org>
Subject: Re: [PATCHSET v4] blk-mq-scheduling framework
Date: Tue, 17 Jan 2017 11:47:12 +0100	[thread overview]
Message-ID: <85B37FBF-4C3F-436B-8883-48E734967732@linaro.org> (raw)
In-Reply-To: <b258d716-5c9a-c999-cec4-6bea38a8b975@fb.com>

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[RESENDING, BECAUSE OF REJECT FROM SERVERS]

> Il giorno 17 gen 2017, alle ore 03:47, Jens Axboe <axboe@fb.com <mailto:axboe@fb.com>> ha scritto:
> 
> On 12/22/2016 08:28 AM, Paolo Valente wrote:
>> 
>>> ...
>>> 
>> 
>> Problem: whereas it seems easy and safe to do somewhere else the
>> simple increment that was done in activate_request, I wonder if it may
>> happen that a request is deactivate before being completed.  In it may
>> happen, then, without a deactivate_request hook, the increments would
>> remain unbalanced.  Or are request completions always guaranteed till
>> no hw/sw components breaks?
> 
> You should be able to do it in get/put_request. But you might need some
> extra tracking, I'd need to double check.

Exactly, AFAICT something extra is apparently needed.  In particular,
get is not ok, because dispatch is a different event (but dispatch is
however an already controlled event), while put could be used,
provided that it is guaranteed to be executed only after dispatch.  If
it is not, then I think that an extra flag or something should be
added to the request.  I don't know whether adding this extra piece
would be worst than adding an extra hook.

> I'm trying to avoid adding
> hooks that we don't truly need, the old interface had a lot of that. If
> you find that you need a hook and it isn't there, feel free to add it.
> activate/deactivate might be a good change.
> 

If my comments above do not trigger any proposal of a better solution,
then I will try by adding only one extra 'deactivate' hook.  Unless
unbalanced hooks are a bad idea too.

Thanks,
Paolo

> -- 
> Jens Axboe


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  parent reply	other threads:[~2017-01-17 10:47 UTC|newest]

Thread overview: 115+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-17  0:12 [PATCHSET v4] blk-mq-scheduling framework Jens Axboe
2016-12-17  0:12 ` [PATCH 1/8] block: move existing elevator ops to union Jens Axboe
2016-12-17  0:12 ` [PATCH 2/8] blk-mq: make mq_ops a const pointer Jens Axboe
2016-12-17  0:12 ` [PATCH 3/8] block: move rq_ioc() to blk.h Jens Axboe
2016-12-20 10:12   ` Paolo Valente
2016-12-20 10:12     ` Paolo Valente
2016-12-20 15:46     ` Jens Axboe
2016-12-20 22:14       ` Jens Axboe
2016-12-17  0:12 ` [PATCH 4/8] blk-mq: un-export blk_mq_free_hctx_request() Jens Axboe
2016-12-17  0:12 ` [PATCH 5/8] blk-mq: export some helpers we need to the scheduling framework Jens Axboe
2016-12-17  0:12 ` [PATCH 6/8] blk-mq-sched: add framework for MQ capable IO schedulers Jens Axboe
2016-12-20 11:55   ` Paolo Valente
2016-12-20 11:55     ` Paolo Valente
2016-12-20 15:45     ` Jens Axboe
2016-12-21  2:22     ` Jens Axboe
2016-12-22 15:20       ` Paolo Valente
2016-12-22 15:20         ` Paolo Valente
2016-12-22  9:59   ` Paolo Valente
2016-12-22  9:59     ` Paolo Valente
2016-12-22 11:13     ` Paolo Valente
2016-12-22 11:13       ` Paolo Valente
2017-01-17  2:47       ` Jens Axboe
2017-01-17  2:47         ` Jens Axboe
2017-01-17 10:13         ` Paolo Valente
2017-01-17 10:13           ` Paolo Valente
2017-01-17 12:38           ` Jens Axboe
2017-01-17 12:38             ` Jens Axboe
2016-12-23 10:12     ` Paolo Valente
2016-12-23 10:12       ` Paolo Valente
2017-01-17  2:47     ` Jens Axboe
2017-01-17  9:17       ` Paolo Valente
2017-01-17  9:17         ` Paolo Valente
2016-12-17  0:12 ` [PATCH 7/8] mq-deadline: add blk-mq adaptation of the deadline IO scheduler Jens Axboe
2016-12-20  9:34   ` Paolo Valente
2016-12-20  9:34     ` Paolo Valente
2016-12-20 15:46     ` Jens Axboe
2016-12-21 11:59   ` Bart Van Assche
2016-12-21 11:59     ` Bart Van Assche
2016-12-21 14:22     ` Jens Axboe
2016-12-22 16:07   ` Paolo Valente
2016-12-22 16:07     ` Paolo Valente
2017-01-17  2:47     ` Jens Axboe
2017-01-17  2:47       ` Jens Axboe
2016-12-22 16:49   ` Paolo Valente
2016-12-22 16:49     ` Paolo Valente
2017-01-17  2:47     ` Jens Axboe
2017-01-20 11:07       ` Paolo Valente
2017-01-20 11:07         ` Paolo Valente
2017-01-20 14:26         ` Jens Axboe
2017-01-20 13:14   ` Paolo Valente
2017-01-20 13:14     ` Paolo Valente
2017-01-20 13:18     ` Paolo Valente
2017-01-20 13:18       ` Paolo Valente
2017-01-20 14:28       ` Jens Axboe
2017-01-20 14:28     ` Jens Axboe
2017-02-01 11:11   ` Paolo Valente
2017-02-01 11:11     ` Paolo Valente
2017-02-02  5:19     ` Jens Axboe
2017-02-02  9:19       ` Paolo Valente
2017-02-02  9:19         ` Paolo Valente
2017-02-02 15:30         ` Jens Axboe
2017-02-02 15:30           ` Jens Axboe
2017-02-02 21:15           ` Paolo Valente
2017-02-02 21:15             ` Paolo Valente
2017-02-02 21:32             ` Jens Axboe
2017-02-02 21:32               ` Jens Axboe
2017-02-07 17:27               ` Paolo Valente
2017-02-07 17:27                 ` Paolo Valente
2017-02-01 11:56   ` Paolo Valente
2017-02-01 11:56     ` Paolo Valente
2017-02-02  5:20     ` Jens Axboe
2017-02-16 10:46   ` Paolo Valente
2017-02-16 10:46     ` Paolo Valente
2017-02-16 15:35     ` Jens Axboe
2017-02-16 15:35       ` Jens Axboe
2016-12-17  0:12 ` [PATCH 8/8] blk-mq-sched: allow setting of default " Jens Axboe
2016-12-19 11:32 ` [PATCHSET v4] blk-mq-scheduling framework Paolo Valente
2016-12-19 11:32   ` Paolo Valente
2016-12-19 15:20   ` Jens Axboe
2016-12-19 15:20     ` Jens Axboe
2016-12-19 15:33     ` Jens Axboe
2016-12-19 18:21     ` Paolo Valente
2016-12-19 18:21       ` Paolo Valente
2016-12-19 21:05       ` Jens Axboe
2016-12-19 21:05         ` Jens Axboe
2016-12-22 15:28         ` Paolo Valente
2016-12-22 15:28           ` Paolo Valente
2017-01-17  2:47           ` Jens Axboe
2017-01-17 10:43             ` Paolo Valente
2017-01-17 10:44             ` Paolo Valente
2017-01-17 10:47             ` Paolo Valente [this message]
2017-01-17 10:49             ` Paolo Valente
2017-01-17 10:49               ` Paolo Valente
2017-01-18 16:14               ` Paolo Valente
2017-01-18 16:14                 ` Paolo Valente
2017-01-18 16:21                 ` Jens Axboe
2017-01-18 16:21                   ` Jens Axboe
2017-01-23 17:04                   ` Paolo Valente
2017-01-23 17:04                     ` Paolo Valente
2017-01-23 17:42                     ` Jens Axboe
2017-01-23 17:42                       ` Jens Axboe
2017-01-25  8:46                       ` Paolo Valente
2017-01-25  8:46                         ` Paolo Valente
2017-01-25 16:13                         ` Jens Axboe
2017-01-25 16:13                           ` Jens Axboe
2017-01-26 14:23                           ` Paolo Valente
2017-01-26 14:23                             ` Paolo Valente
2016-12-22 16:23 ` Bart Van Assche
2016-12-22 16:52   ` Omar Sandoval
2016-12-22 16:52     ` Omar Sandoval
2016-12-22 16:57     ` Bart Van Assche
2016-12-22 16:57       ` Bart Van Assche
2016-12-22 17:12       ` Omar Sandoval
2016-12-22 17:39         ` Bart Van Assche
2016-12-22 17:39           ` Bart Van Assche

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