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Mon, 25 Mar 2024 05:12:11 GMT Received: from smtpav05.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 848E458056; Mon, 25 Mar 2024 05:12:09 +0000 (GMT) Received: from smtpav05.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1DC5B58052; Mon, 25 Mar 2024 05:12:07 +0000 (GMT) Received: from [9.124.31.56] (unknown [9.124.31.56]) by smtpav05.dal12v.mail.ibm.com (Postfix) with ESMTP; Mon, 25 Mar 2024 05:12:06 +0000 (GMT) Message-ID: <59224c52-1864-4920-8bac-9da308d257db@linux.ibm.com> Date: Mon, 25 Mar 2024 10:42:05 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/2] sched/fair: Use helper functions to access rd->overload To: Qais Yousef Cc: mingo@kernel.org, peterz@infradead.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, linux-kernel@vger.kernel.org, vschneid@redhat.com, qperret@google.com References: <20240322141632.28654-1-sshegde@linux.ibm.com> <20240322141632.28654-3-sshegde@linux.ibm.com> <20240324011620.f3mmywh44htvlb5m@airbuntu> Content-Language: en-US From: Shrikanth Hegde In-Reply-To: <20240324011620.f3mmywh44htvlb5m@airbuntu> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: FKqsdZJVIGDZrd7MNagkz52Fii323nvt X-Proofpoint-GUID: eJ9BfbFP_vdRx9wKz1EleH_Up7cgWi7F X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-03-25_02,2024-03-21_02,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 mlxscore=0 impostorscore=0 bulkscore=0 adultscore=0 suspectscore=0 spamscore=0 malwarescore=0 phishscore=0 priorityscore=1501 clxscore=1011 mlxlogscore=780 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2403210000 definitions=main-2403250027 On 3/24/24 6:46 AM, Qais Yousef wrote: > On 03/22/24 19:46, Shrikanth Hegde wrote: >> >> if (!env->sd->parent) { >> /* update overload indicator if we are at root domain */ >> - if (READ_ONCE(env->dst_rq->rd->overload) != (sg_status & SG_OVERLOAD)) >> - WRITE_ONCE(env->dst_rq->rd->overload, sg_status & SG_OVERLOAD); >> + if (is_rd_overloaded(env->dst_rq->rd) != (sg_status & SG_OVERLOAD)) >> + set_rd_overload_status(env->dst_rq->rd, >> + sg_status & SG_OVERLOAD); > > A bit picky, but.. > > Wouldn't it be better to encapsulate the check of whether we're writing a new > value inside set_rd_overload_status()? Only write if it the value changed and > all future users wouldn't care then. > > I think no need to wrap the line too. > Yes. Makes sense all the places do the check and update, can be wrapped. I will send out v3. >> >> /* Update over-utilization (tipping point, U >= 0) indicator */ >> set_rd_overutilized_status(env->dst_rq->rd, >> @@ -12344,7 +12345,7 @@ static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf) >> rcu_read_lock(); >> sd = rcu_dereference_check_sched_domain(this_rq->sd); >> >> - if (!READ_ONCE(this_rq->rd->overload) || >> + if (!is_rd_overloaded(this_rq->rd) || >> (sd && this_rq->avg_idle < sd->max_newidle_lb_cost)) { >> >> if (sd) >> @@ -2518,8 +2528,8 @@ static inline void add_nr_running(struct rq *rq, unsigned count) >> >> #ifdef CONFIG_SMP >> if (prev_nr < 2 && rq->nr_running >= 2) { >> - if (!READ_ONCE(rq->rd->overload)) >> - WRITE_ONCE(rq->rd->overload, 1); >> + if (!is_rd_overloaded(rq->rd)) >> + set_rd_overload_status(rq->rd, 1); > > While at it, could you write SG_OVERLOAD instead of 1? Done. > > Both patches LGTM otherwise > > Reviewed-by: Qais Yousef > >