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[103.229.16.4]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-387d2585f34sm2065812a91.17.2026.07.07.21.09.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 07 Jul 2026 21:09:24 -0700 (PDT) Message-ID: <4430befd-2d2c-422f-98b5-5947bb633937@oss.qualcomm.com> Date: Wed, 8 Jul 2026 12:09:18 +0800 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 v1] cpufreq: Make cpufreq_update_pressure() fall back to cpuinfo.max_freq To: Viresh Kumar , "Rafael J. Wysocki" Cc: Linux PM , Vincent Guittot , LKML , Srinivas Pandruvada , Dhruva Gole , Lukasz Luba , Qais Yousef , Ingo Molnar , zhongqiu.han@oss.qualcomm.com References: <5086499.GXAFRqVoOG@rafael.j.wysocki> Content-Language: en-US From: Zhongqiu Han In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Proofpoint-ORIG-GUID: AP5gGaieMGjbNDXbezmtg7GfndiiDxH_ X-Proofpoint-Spam-Info: AW1haW4tMjYwNzA4MDAzNiBTYWx0ZWRfX8koBlQ6KqfaS MgAmiNLiXgLu6bCAGjPozlq002X90Leb3XX/K+gqLXjjFZIbGTOCC7oDnfrTdsSFzWvkjX7n+Bd cfGna7JtqK7qpamhsyjH4nRYijN7wrY= X-Authority-Analysis: v=2.4 cv=SZfHsPRu c=1 sm=1 tr=0 ts=6a4dcd75 cx=c_pps a=UNFcQwm+pnOIJct1K4W+Mw==:117 a=nuhDOHQX5FNHPW3J6Bj6AA==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=eoimf2acIAo5FJnRuUoq:22 a=VwQbUJbxAAAA:8 a=pGLkceISAAAA:8 a=QyXUC8HyAAAA:8 a=KKAkSRfTAAAA:8 a=EUspDBNiAAAA:8 a=w9sFvXK1ldvP2PC-LusA:9 a=QEXdDO2ut3YA:10 a=uKXjsCUrEbL0IQVhDsJ9:22 a=cvBusfyB2V15izCimMoJ:22 X-Proofpoint-GUID: AP5gGaieMGjbNDXbezmtg7GfndiiDxH_ X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzA4MDAzNiBTYWx0ZWRfX3f7rEiHtxEq1 TQCt9Ibh1o1tXrHewqrHRANmUrH/VR6ZKnmN5x2shaZmO1Bh5OHr+gmaYD1BTjsY6MZ/4tiXmA7 wPe4VVzIdlu2FiUlL5uw12rC7zQ+hhukKEDLYAodtYeGi+PkkkP94EeAuyrpBGEgiShccaYoDEq VLBM6LZPq8e0uOSz6CIW1N8hJstrjwdA7F4FWWTc6NT9wZH2EW/v6DL/3buD/ZijUPQCjSgX1zk yt82lLgidOvZF831dHeZO71XRIdVBwbCLs3MNasit/ejvWj/ty+Yu9XhUwwJoB7YUwTwRgMbKjT 3P91DokBSMqMKa2fix3xNp6AmgcNkX9zGp3opRzMleXqGKFGavTtW+MsiqjaZ6rV3xF12lJ4Vxj 8nPjg7os1xS1kJqxJJO7QbELIvW00yA/qaQBnveqAa1ChR7ELCttaKb3wEeTsE7tC8F9L2BP+qH Zn/07XPvOskkvVTGd6g== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-07_06,2026-07-06_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 malwarescore=0 bulkscore=0 spamscore=0 adultscore=0 lowpriorityscore=0 phishscore=0 clxscore=1015 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607080036 On 7/8/2026 11:44 AM, Viresh Kumar wrote: > On 07-07-26, 19:25, Rafael J. Wysocki wrote: >> From: Rafael J. Wysocki >> >> If arch_scale_freq_ref() is not defined for a given arch (like x86, for >> example), cpufreq_update_pressure() will always set cpufreq_pressure to >> zero for all CPUs in the system, which is generally problematic on >> systems with asymmetric capacity [1]. >> >> However, in the absence of arch_scale_freq_ref(), it is reasonable >> to assume that cpuinfo.max_freq is the maximum sustainable frequency >> for the given cpufreq policy. Moreover, there are cases in which >> arch_scale_freq_ref() would need to be defined to return essentially >> the cpuinfo.max_freq value anyway (for example, intel_pstate on >> hybrid platforms). >> >> For the above reasons, update cpufreq_update_pressure() to fall back to >> using cpuinfo.max_freq as the reference frequency if zero is returned by >> arch_scale_freq_ref(). >> >> Fixes: 75d659317bb1 ("cpufreq: Add a cpufreq pressure feedback for the scheduler") >> Link: https://lore.kernel.org/lkml/CAKfTPtBuRLfYNnR4w--cFZYZy-R8gaPEgVwCcaMmbCcJ2H-muQ@mail.gmail.com/ [1] >> Signed-off-by: Rafael J. Wysocki >> --- >> drivers/cpufreq/cpufreq.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> --- a/drivers/cpufreq/cpufreq.c >> +++ b/drivers/cpufreq/cpufreq.c >> @@ -2590,6 +2590,9 @@ static void cpufreq_update_pressure(stru >> >> cpu = cpumask_first(policy->related_cpus); >> max_freq = arch_scale_freq_ref(cpu); >> + if (!max_freq) >> + max_freq = policy->cpuinfo.max_freq; >> + >> capped_freq = policy->max; >> >> /* > > Acked-by: Viresh Kumar > Reviewed-by: Zhongqiu Han -- Thx and BRs, Zhongqiu Han