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Mon, 4 May 2026 13:31:05 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 4JNRBJmf+GkgHAAAD6G6ig (envelope-from ); Mon, 04 May 2026 13:31:05 +0000 Message-ID: Date: Mon, 4 May 2026 15:31:04 +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: [RFC PATCH] drm/gm12u320: Replace system_long_wq with system_dfl_long_wq To: Marco Crivellari , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Cc: Tejun Heo , Lai Jiangshan , Frederic Weisbecker , Sebastian Andrzej Siewior , Michal Hocko , Hans de Goede , Maarten Lankhorst , Maxime Ripard , David Airlie , Simona Vetter References: <20260430091532.115846-1-marco.crivellari@suse.com> Content-Language: en-US From: Thomas Zimmermann Autocrypt: addr=tzimmermann@suse.de; keydata= xsBNBFs50uABCADEHPidWt974CaxBVbrIBwqcq/WURinJ3+2WlIrKWspiP83vfZKaXhFYsdg XH47fDVbPPj+d6tQrw5lPQCyqjwrCPYnq3WlIBnGPJ4/jreTL6V+qfKRDlGLWFjZcsrPJGE0 BeB5BbqP5erN1qylK9i3gPoQjXGhpBpQYwRrEyQyjuvk+Ev0K1Jc5tVDeJAuau3TGNgah4Yc hdHm3bkPjz9EErV85RwvImQ1dptvx6s7xzwXTgGAsaYZsL8WCwDaTuqFa1d1jjlaxg6+tZsB 9GluwvIhSezPgnEmimZDkGnZRRSFiGP8yjqTjjWuf0bSj5rUnTGiyLyRZRNGcXmu6hjlABEB AAHNJ1Rob21hcyBaaW1tZXJtYW5uIDx0emltbWVybWFubkBzdXNlLmRlPsLAjgQTAQgAOAIb AwULCQgHAgYVCgkICwIEFgIDAQIeAQIXgBYhBHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJftODH AAoJEGgNwR1TC3ojx1wH/0hKGWugiqDgLNXLRD/4TfHBEKmxIrmfu9Z5t7vwUKfwhFL6hqvo lXPJJKQpQ2z8+X2vZm/slsLn7J1yjrOsoJhKABDi+3QWWSGkaGwRJAdPVVyJMfJRNNNIKwVb U6B1BkX2XDKDGffF4TxlOpSQzdtNI/9gleOoUA8+jy8knnDYzjBNOZqLG2FuTdicBXblz0Mf vg41gd9kCwYXDnD91rJU8tzylXv03E75NCaTxTM+FBXPmsAVYQ4GYhhgFt8S2UWMoaaABLDe 7l5FdnLdDEcbmd8uLU2CaG4W2cLrUaI4jz2XbkcPQkqTQ3EB67hYkjiEE6Zy3ggOitiQGcqp j//OwE0EWznS4AEIAMYmP4M/V+T5RY5at/g7rUdNsLhWv1APYrh9RQefODYHrNRHUE9eosYb T6XMryR9hT8XlGOYRwKWwiQBoWSDiTMo/Xi29jUnn4BXfI2px2DTXwc22LKtLAgTRjP+qbU6 3Y0xnQN29UGDbYgyyK51DW3H0If2a3JNsheAAK+Xc9baj0LGIc8T9uiEWHBnCH+RdhgATnWW GKdDegUR5BkDfDg5O/FISymJBHx2Dyoklv5g4BzkgqTqwmaYzsl8UxZKvbaxq0zbehDda8lv hFXodNFMAgTLJlLuDYOGLK2AwbrS3Sp0AEbkpdJBb44qVlGm5bApZouHeJ/+n+7r12+lqdsA EQEAAcLAdgQYAQgAIAIbDBYhBHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJftOH6AAoJEGgNwR1T C3ojVSkIALpAPkIJPQoURPb1VWjh34l0HlglmYHvZszJWTXYwavHR8+k6Baa6H7ufXNQtThR yIxJrQLW6rV5lm7TjhffEhxVCn37+cg0zZ3j7zIsSS0rx/aMwi6VhFJA5hfn3T0TtrijKP4A SAQO9xD1Zk9/61JWk8OysuIh7MXkl0fxbRKWE93XeQBhIJHQfnc+YBLprdnxR446Sh8Wn/2D Ya8cavuWf2zrB6cZurs048xe0UbSW5AOSo4V9M0jzYI4nZqTmPxYyXbm30Kvmz0rYVRaitYJ 4kyYYMhuULvrJDMjZRvaNe52tkKAvMevcGdt38H4KSVXAylqyQOW5zvPc4/sq9c= In-Reply-To: <20260430091532.115846-1-marco.crivellari@suse.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Score: -4.30 X-Spam-Level: X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; ARC_NA(0.00)[]; RCPT_COUNT_TWELVE(0.00)[13]; MIME_TRACE(0.00)[0:+]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCVD_TLS_ALL(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[kernel.org,gmail.com,linutronix.de,suse.com,linux.intel.com,ffwll.ch]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; URIBL_BLOCKED(0.00)[suse.com:url,suse.com:email,imap1.dmz-prg2.suse.org:helo,suse.de:mid,suse.de:email]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.de:mid,suse.de:email,suse.com:url,suse.com:email] X-Spam-Flag: NO Am 30.04.26 um 11:15 schrieb Marco Crivellari: > Currently the code enqueue work items using {queue|mod}_delayed_work(), > using system_long_wq. This workqueue should be used when long works are > expected, but it is a per-cpu workqueue. > > This is important because queue_delayed_work() queue the work using: > > queue_delayed_work_on(WORK_CPU_UNBOUND, ...); > > Note that WORK_CPU_UNBOUND = NR_CPUS. > > This would end up calling __queue_delayed_work() that does: > > if (housekeeping_enabled(HK_TYPE_TIMER)) { > // [....] > } else { > if (likely(cpu == WORK_CPU_UNBOUND)) > add_timer_global(timer); > else > add_timer_on(timer, cpu); > } > > So when cpu == WORK_CPU_UNBOUND the timer is global and is > not using a specific CPU. Later, when __queue_work() is called: > > if (req_cpu == WORK_CPU_UNBOUND) { > if (wq->flags & WQ_UNBOUND) > cpu = wq_select_unbound_cpu(raw_smp_processor_id()); > else > cpu = raw_smp_processor_id(); > } > > Because the wq is not unbound, it takes the CPU where the timer > fired and enqueue the work on that CPU. > The consequence of all of this is that the work can run anywhere, > depending on where the timer fired. > > Recently, a new unbound workqueue specific for long running work has > been added: > > c116737e972e ("workqueue: Add system_dfl_long_wq for long unbound works") > > So change system_long_wq with system_dfl_long_wq so that the work may > benefit from scheduler task placement. > > Signed-off-by: Marco Crivellari Reviewed-by: Thomas Zimmermann > --- > drivers/gpu/drm/tiny/gm12u320.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/tiny/gm12u320.c b/drivers/gpu/drm/tiny/gm12u320.c > index d73dfebb4353..4ad074337af0 100644 > --- a/drivers/gpu/drm/tiny/gm12u320.c > +++ b/drivers/gpu/drm/tiny/gm12u320.c > @@ -388,7 +388,7 @@ static void gm12u320_fb_update_work(struct work_struct *work) > * We must draw a frame every 2s otherwise the projector > * switches back to showing its logo. > */ > - queue_delayed_work(system_long_wq, &gm12u320->fb_update.work, > + queue_delayed_work(system_dfl_long_wq, &gm12u320->fb_update.work, > msecs_to_jiffies(IDLE_TIMEOUT)); > > return; > @@ -427,7 +427,8 @@ static void gm12u320_fb_mark_dirty(struct drm_framebuffer *fb, > mutex_unlock(&gm12u320->fb_update.lock); > > if (wakeup) > - mod_delayed_work(system_long_wq, &gm12u320->fb_update.work, 0); > + mod_delayed_work(system_dfl_long_wq, > + &gm12u320->fb_update.work, 0); > > if (old_fb) > drm_framebuffer_put(old_fb); -- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)