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[79.51.196.100]) by smtp.gmail.com with ESMTPSA id bt15-20020a170906b14f00b00a51eed4f0d7sm8575225ejb.130.2024.04.24.09.56.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 Apr 2024 09:56:10 -0700 (PDT) Message-ID: <99c1761a-9c00-4167-86e5-8a69cb6d9e5d@redhat.com> Date: Wed, 24 Apr 2024 18:56:08 +0200 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] sched/fair: fix dlserver duplicate start and stop To: "Vineeth Pillai (Google)" , Daniel Bristot de Oliveira , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot Cc: Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , linux-kernel@vger.kernel.org, Luca Abeni , Tommaso Cucinotta , Thomas Gleixner , Joel Fernandes , Shuah Khan , Phil Auld , Suleiman Souhlal , Youssef Esmat References: <20240412192304.3201847-1-vineeth@bitbyteword.org> Content-Language: en-US, pt-BR, it-IT From: Daniel Bristot de Oliveira In-Reply-To: <20240412192304.3201847-1-vineeth@bitbyteword.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/12/24 21:23, Vineeth Pillai (Google) wrote: > dlserver is started when a cfs task is enqueued to an empty runqueue. > Similarly dlserver is stopped when the last cfs task is dequeued. But > this logic doesn't take care of the cfs throttling scenarios where the > root cfs runqueue's h_nr_running stays zero while enqueue/dequeue can > happen on throttled runqueues. This causes duplicate calls to start/stop > and causes issues with deadline logic. One example is a WARN_ON in > task_non_contending because of duplicate calls to dl_server_stop(). > > WARNING kernel: [ 1970.747755] ------------[ cut here ]------------ > WARNING kernel: [ 1970.747767] WARNING: CPU: 0 PID: 14202 at kernel/sched/deadline.c:352 task_non_contending+0x404/0x500 > > WARNING kernel: [ 1970.747868] CPU: 0 PID: 14202 Comm: tpm_manager_cli Tainted: G W 5.15.152-22017-ga797d64dcd15 #1 > WARNING kernel: [ 1970.747874] Hardware name: HP Meep/Meep, BIOS Google_Meep.11297.250.0 01/25/2021 > WARNING kernel: [ 1970.747877] RIP: 0010:task_non_contending+0x404/0x500 > > WARNING kernel: [ 1970.747910] Call Trace: > WARNING kernel: [ 1970.747914] > WARNING kernel: [ 1970.747918] ? __warn+0xa3/0x131 > WARNING kernel: [ 1970.747923] ? task_non_contending+0x404/0x500 > WARNING kernel: [ 1970.747927] ? report_bug+0x97/0xfa > WARNING kernel: [ 1970.747932] ? handle_bug+0x41/0x66 > WARNING kernel: [ 1970.747937] ? exc_invalid_op+0x1b/0x4b > WARNING kernel: [ 1970.747941] ? asm_exc_invalid_op+0x16/0x20 > WARNING kernel: [ 1970.747946] ? task_non_contending+0x404/0x500 > WARNING kernel: [ 1970.747949] ? dequeue_dl_entity+0x112/0x2cd > WARNING kernel: [ 1970.747952] dl_server_stop+0x17/0x2b > WARNING kernel: [ 1970.747956] dequeue_task_fair+0x262/0x4c4 > WARNING kernel: [ 1970.747962] __schedule+0x17c/0xf13 > WARNING kernel: [ 1970.747966] ? update_load_avg+0x9b/0x611 > WARNING kernel: [ 1970.747970] schedule+0x4e/0xd0 > WARNING kernel: [ 1970.747974] schedule_hrtimeout_range_clock+0x10f/0x126 > WARNING kernel: [ 1970.747977] ? add_wait_queue+0x4d/0x84 > WARNING kernel: [ 1970.747982] poll_schedule_timeout+0x33/0x50 > WARNING kernel: [ 1970.747987] do_sys_poll+0x4a3/0x626 > WARNING kernel: [ 1970.747993] ? __se_sys_ppoll+0xdf/0xdf > WARNING kernel: [ 1970.748000] __se_sys_poll+0x70/0xf7 > WARNING kernel: [ 1970.748003] do_syscall_64+0x51/0xa1 > WARNING kernel: [ 1970.748007] entry_SYSCALL_64_after_hwframe+0x5c/0xc6 > WARNING kernel: [ 1970.748012] RIP: 0033:0x7bc815769510 I saw that as well.... but from a robot.. not with a reproducer. > dlserver should be started on an idle root cfs rq, when > - enqueue on a non-throttled cfs_rq causing the root cfs rq to > go non-idle, or > - untthrottle results in the root cfs rq to go non-idle. > > Similarly dlserver should be stopped on a non-idle root cfs rq, when > - dequeue on a non-throttled cfs_rq causing the root cfs rq to > go idle, or > - throttle results in the root cfs rq to go idle. seem to make sense, I will add this check on v7. Btw, as this is an ongoing thread discussion, instead of sending a patch, next time, please reply to the patchset... it is easier for everybody to keep track. -- Daniel