Re: Top syscalls

[Hien Nguyen <hien at us dot ibm dot com>]

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.
>
>
>  
>
> > [...]
> > 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.