linux-kernel - Re: [PATCH] interrupt: discover and disable very frequent interrupts

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Date:   Sun, 9 Oct 2022 09:31:36 +0800
From:   "Zhang Xincheng" <zhangxincheng@...ontech.com>
To:     "maz" <maz@...nel.org>
Cc:     "tglx" <tglx@...utronix.de>,
        "linux-kernel" <linux-kernel@...r.kernel.org>,
        "oleksandr" <oleksandr@...alenko.name>,
        "Hans de Goede" <hdegoede@...hat.com>,
        "bigeasy" <bigeasy@...utronix.de>,
        "mark.rutland" <mark.rutland@....com>,
        "michael" <michael@...le.cc>
Subject: Re: [PATCH] interrupt: discover and disable very frequent interrupts

> Again: what makes you think that it is better to kill the interrupt
> than suffering a RCU stall? Yes, that's a lot of interrupts. But
> killing it and risking the whole system isn't an acceptable outcome.

It's really not good to kill interrupts directly. Perhaps a better way is
to report it and let the system administrator decide what to do with it.

+ if((desc->gap_count & 0xffff0000) == 0)
+ desc->gap_time = get_jiffies_64();
+
+ desc->gap_count ++;
+
+ if((desc->gap_count & 0x0000ffff) >= 2000) {
+ if((get_jiffies_64() - desc->gap_time) < HZ) {
+ desc->gap_count += 0x00010000;
+ desc->gap_count &= 0xffff0000;
+ } else {
+ desc->gap_count = 0;
+ }
+
+ if((desc->gap_count >> 16) > 30) {
+ __report_bad_irq(desc, action_ret, KERN_ERR "irq %d: triggered too frequently\n");
+ }
+ }
+


Thanks,

             Zhang Xincheng