From b413db50436481699acdeb0571e57f43ee7c5dda Mon Sep 17 00:00:00 2001 From: Corey Minyard Date: Thu, 10 Oct 2019 10:12:22 +0800 Subject: [PATCH] ipmi_si: Only schedule continuously in the thread in maintenance mode [ Upstream commit 340ff31ab00bca5c15915e70ad9ada3030c98cf8 ] ipmi_thread() uses back-to-back schedule() to poll for command completion which, on some machines, can push up CPU consumption and heavily tax the scheduler locks leading to noticeable overall performance degradation. This was originally added so firmware updates through IPMI would complete in a timely manner. But we can't kill the scheduler locks for that one use case. Instead, only run schedule() continuously in maintenance mode, where firmware updates should run. Signed-off-by: Corey Minyard Signed-off-by: Sasha Levin Signed-off-by: Yang Yingliang --- drivers/char/ipmi/ipmi_si_intf.c | 24 +++++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-) diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c index 1c71c0dfa355..ba330380e5da 100644 --- a/drivers/char/ipmi/ipmi_si_intf.c +++ b/drivers/char/ipmi/ipmi_si_intf.c @@ -221,6 +221,9 @@ struct smi_info { */ bool irq_enable_broken; + /* Is the driver in maintenance mode? */ + bool in_maintenance_mode; + /* * Did we get an attention that we did not handle? */ @@ -1013,11 +1016,20 @@ static int ipmi_thread(void *data) spin_unlock_irqrestore(&(smi_info->si_lock), flags); busy_wait = ipmi_thread_busy_wait(smi_result, smi_info, &busy_until); - if (smi_result == SI_SM_CALL_WITHOUT_DELAY) + if (smi_result == SI_SM_CALL_WITHOUT_DELAY) { ; /* do nothing */ - else if (smi_result == SI_SM_CALL_WITH_DELAY && busy_wait) - schedule(); - else if (smi_result == SI_SM_IDLE) { + } else if (smi_result == SI_SM_CALL_WITH_DELAY && busy_wait) { + /* + * In maintenance mode we run as fast as + * possible to allow firmware updates to + * complete as fast as possible, but normally + * don't bang on the scheduler. + */ + if (smi_info->in_maintenance_mode) + schedule(); + else + usleep_range(100, 200); + } else if (smi_result == SI_SM_IDLE) { if (atomic_read(&smi_info->need_watch)) { schedule_timeout_interruptible(100); } else { @@ -1025,8 +1037,9 @@ static int ipmi_thread(void *data) __set_current_state(TASK_INTERRUPTIBLE); schedule(); } - } else + } else { schedule_timeout_interruptible(1); + } } return 0; } @@ -1201,6 +1214,7 @@ static void set_maintenance_mode(void *send_info, bool enable) if (!enable) atomic_set(&smi_info->req_events, 0); + smi_info->in_maintenance_mode = enable; } static void shutdown_smi(void *send_info); -- GitLab