Top syscalls

[Hien Nguyen]

Frank Ch. Eigler wrote:

>I expect that when the system call tapset is finally constructed,
>strings such as the plain system call names will be made available in
>the new probe point aliases.  Is anyone now working on this?
>
>  
>
Yes, system call tap set should export plain name. Kevin is working on it.

>Yeah, no wonder this, repeated 20 times, is running out of the
>MAXACTION quota, which is around 1000 statements.  I hope we can think
>of a way of expressing "top N" type queries using statistics objects,
>or a sorting primitive, or something.
>  
>

A built in assoc array sorting function would be great.

>Be aware that this processing loop in fact does/should (bug #1275)
>lock the syscall_count array for the duration of the iteration.  That
>that means that concurent processes on other CPUs trying to perform
>syscalls will be held in a spinlock.  So the MAXACTION limit performs
>a useful function even in this case.
>
>
>  
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>>[...]
>>probe kernel.function("sys_*") {
>>	if (pid() != get_daemon_pid())
>>		accumulate ()
>>}
>>    
>>
>
>Did you find that this filtering was necessary?  Was stpd showing up a
>lot?  I thought it had learned to batch its kernel-to-user message
>passing, so as to produce a smaller footprint.
>
>  
>
Actually, we don't need to do that filtering.