From: Dave Hansen <[email protected]>
Date: Fri, 23 Aug 2002 09:39:13 -0700
Where are interrupts disabled? I just went through a set of kernprof
data and traced up the call graph. In the most common __kfree_skb
case, I do not believe that it has interupts disabled. I could be
wrong, but I didn't see it.
>That's completely right. interrupts should never be disabled when
>__kfree_skb is executed. It used to be possible when we allowed
>it to be invoked from interrupt handlers, but that is illegal and
>we have kfree_skb_irq which just reschedules the actual __kfree_skb
>to a software interrupt.
>So I agree with you, Mala's claims seem totally bogus and not well
>founded at all.
To name a few, interrupts are disabled when skbs are put back to the
hot_list
and when the cache list is accessed in the slab allocator. Am I missing
something? Please help me to understand.
Regards,
Mala
Mala Anand
IBM Linux Technology Center - Kernel Performance
E-mail:[email protected]
http://www-124.ibm.com/developerworks/opensource/linuxperf
http://www-124.ibm.com/developerworks/projects/linuxperf
Phone:838-8088; Tie-line:678-8088
From: "Mala Anand" <[email protected]>
Date: Fri, 23 Aug 2002 18:38:59 -0500
To name a few, interrupts are disabled when skbs are put back to the
hot_list
A few cycles, at best, it should not be enough to skew the profiling
and when the cache list is accessed in the slab allocator. Am I missing
something? Please help me to understand.
Which means if this were enough to skew profiling, it would make the
program counter of the interrupt enable instruction in the SLAB code
show up clearly in the profiles.