Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Content-Type: text/plain;
        charset=us-ascii
Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.11\))
Subject: Re: [PATCH V10 1/8] block, bfq: split sync bfq_queues on a
 per-actuator basis
From:   Paolo Valente <paolo.valente@linaro.org>
In-Reply-To: <3E955C95-3912-46D0-A48C-9709F094FD0D@linaro.org>
Date:   Wed, 21 Dec 2022 11:30:35 +0100
Cc:     Jens Axboe <axboe@kernel.dk>,
        linux-block <linux-block@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Arie van der Hoeven <arie.vanderhoeven@seagate.com>,
        Rory Chen <rory.c.chen@seagate.com>,
        Glen Valante <glen.valante@linaro.org>,
        Gabriele Felici <felicigb@gmail.com>,
        Carmine Zaccagnino <carmine@carminezacc.com>
Content-Transfer-Encoding: quoted-printable
Message-Id: <918DD21A-0099-4EF9-955B-CAED2A3F8947@linaro.org>
References: <20221209094442.36896-1-paolo.valente@linaro.org>
 <20221209094442.36896-2-paolo.valente@linaro.org>
 <cd41583b-ef11-a3b7-1e39-c4a224050c7d@opensource.wdc.com>
 <60582F89-8020-4468-80FE-BC52202D1129@linaro.org>
 <eb58939f-567e-c0c1-bafb-383f18f3d58e@opensource.wdc.com>
 <3E955C95-3912-46D0-A48C-9709F094FD0D@linaro.org>
To:     Damien Le Moal <damien.lemoal@opensource.wdc.com>
Precedence: bulk


> Il giorno 21 dic 2022, alle ore 11:13, Paolo Valente =
<paolo.valente@linaro.org> ha scritto:
>=20
>=20
>=20
>> Il giorno 21 dic 2022, alle ore 01:50, Damien Le Moal =
<damien.lemoal@opensource.wdc.com> ha scritto:
>>=20
>> On 2022/12/20 22:10, Paolo Valente wrote:
>>>>> -	/*
>>>>> -	 * Does queue (or any parent entity) exceed number of requests =
that
>>>>> -	 * should be available to it? Heavily limit depth so that it =
cannot
>>>>> -	 * consume more available requests and thus starve other =
entities.
>>>>> -	 */
>>>>> -	if (bfqq && bfqq_request_over_limit(bfqq, limit))
>>>>> -		depth =3D 1;
>>>>> +	for (act_idx =3D 0; act_idx < bfqd->num_actuators; act_idx++) {
>>>>> +		struct bfq_queue *bfqq =3D
>>>>> +			bic ? bic_to_bfqq(bic, op_is_sync(opf), act_idx) =
: NULL;
>>>>=20
>>>> Commented already: why not add a "if (!bfqq) return NULL;" in
>>>> bic_to_bfqq() ?
>>>=20
>>> You have probably missed my reply on this.  The problem is that your
>>> proposal would improve code (only) here, but it would entail the =
above
>>> control for all the other invocations, for which it is useless :(
>>=20
>> But then you have *a lot* of "if (bfqd)" tests that are useless =
elsewhere since
>> bic_to_bfqq() never returns NULL.
>>=20
>=20
> I'm probably misunderstanding your point, sorry.  Could you point me
> to one of the places where there is the useless control that would go
> away if we add your proposed control inside bic_to_bfqq?

You had already done that in a following email, sorry.  I have replied
to that email of yours.

Thanks,
Paolo