From: Joel Fernandes <joelaf@lab126.com>
To: <linux-rt-users@vger.kernel.org>
Subject: why does this irqsoff tracer output show interrupts disabled between irq to softirq transition?
Date: Tue, 1 Mar 2016 21:37:59 -0800 [thread overview]
Message-ID: <56D67C37.10207@lab126.com> (raw)
Hi,
I am using the irqsoff tracer on a (slightly old) kernel and I am seeing something like this.
As you can see, after servicing the hrtimer_interrupt, and calling irq_exit(), a softirq runs.
But the softirq (which happens to be run_timer_softirq) is being called with interrupts
disabled, - but from my understanding, interrupts are to remain enabled during softirq
operation (unless ofcourse a spinlock is shared between a softirq and an irq handler and
someone calls spinlock_irq_save).
So considering this, does the below makes sense? Thanks for any insight!
mmcqd/0-1435 0d.h1 182us : preempt_count_add <-_raw_spin_lock
mmcqd/0-1435 0d.h2 182us : enqueue_hrtimer <-__run_hrtimer
mmcqd/0-1435 0d.h2 183us : _raw_spin_unlock <-hrtimer_interrupt
mmcqd/0-1435 0d.h2 183us : preempt_count_sub <-_raw_spin_unlock
mmcqd/0-1435 0d.h1 184us : tick_program_event <-hrtimer_interrupt
mmcqd/0-1435 0d.h1 184us : clockevents_program_event <-tick_program_event
mmcqd/0-1435 0d.h1 184us : ktime_get <-clockevents_program_event
mmcqd/0-1435 0d.h1 185us : lapic_next_deadline <-clockevents_program_event
mmcqd/0-1435 0d.h1 186us : irq_exit <-smp_apic_timer_interrupt
mmcqd/0-1435 0d.h1 186us : irqtime_account_irq <-irq_exit
mmcqd/0-1435 0d.h1 187us : preempt_count_sub <-irq_exit
mmcqd/0-1435 0d..1 187us : __do_softirq <-irq_exit
mmcqd/0-1435 0d..1 188us : msecs_to_jiffies <-__do_softirq
mmcqd/0-1435 0d..1 188us : irqtime_account_irq <-__do_softirq
mmcqd/0-1435 0d..1 188us : __local_bh_disable_ip <-__do_softirq
mmcqd/0-1435 0d.s1 190us : preempt_count_add <-_raw_spin_lock_irq
mmcqd/0-1435 0d.s2 191us+: _raw_spin_unlock_irq <-run_timer_softirq
mmcqd/0-1435 0d.s1 194us : preempt_count_add <-_raw_read_lock_irqsave
mmcqd/0-1435 0d.s2 195us+: _raw_read_unlock_irqrestore <-cpufreq_cpu_get
mmcqd/0-1435 0d.s1 201us : preempt_count_add <-_raw_spin_lock_irqsave
mmcqd/0-1435 0d.s2 202us : _raw_spin_unlock_irqrestore <-cpufreq_stats_update
mmcqd/0-1435 0d.s1 203us : preempt_count_add <-_raw_spin_lock_irqsave
mmcqd/0-1435 0d.s2 203us+: _raw_spin_unlock_irqrestore <-cpufreq_stat_notifier_trans
mmcqd/0-1435 0d.s1 205us : preempt_count_add <-_raw_spin_lock_irqsave
mmcqd/0-1435 0d.s2 205us : detach_if_pending <-mod_timer_pinned
mmcqd/0-1435 0d.s2 206us : internal_add_timer <-mod_timer_pinned
mmcqd/0-1435 0d.s2 207us : __internal_add_timer <-internal_add_timer
next reply other threads:[~2016-03-02 5:38 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-02 5:37 Joel Fernandes [this message]
2016-03-05 7:19 ` why does this irqsoff tracer output show interrupts disabled between irq to softirq transition? Joel Fernandes
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=56D67C37.10207@lab126.com \
--to=joelaf@lab126.com \
--cc=linux-rt-users@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).