Re: [PATCH] perf: add 'perf bench syscall'

[Josh Poimboeuf]

On Mon, Jun 20, 2016 at 12:16:22PM -0700, Andy Lutomirski wrote:
> On Mon, Jun 20, 2016 at 11:00 AM, Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:
> 
> >
> > From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> > Subject: [PATCH] perf: add 'perf bench syscall'
> >
> > Add a basic 'perf bench syscall' benchmark which does a getppid() system
> > call in a tight loop.
> >
> 
> My one suggestion would be to use a different syscall than getppid(),
> as getppid() can have unusual performance characteristics on kernels
> with pid namespaces enabled.  I'm a fan of prctl(-1, 0, 0, 0, 0).

Hm, can you elaborate on the unusual performance characteristics of
getppid()?  The code seems pretty minimal.

prctl() actually seems much worse to me, because of all the security
module cruft.

-- 
Josh