This is the mail archive of the
systemtap@sourceware.org
mailing list for the systemtap project.
Re: Some newbie questions
Hi -
On Wed, Aug 17, 2016 at 09:30:38PM +0300, Avi Kivity wrote:
> [...]
> >>My load indeed calls epoll_wait() at a high rate, with zero timeout.
> >[...]
> Yes. It's not very common, but some high throughput or latency
> sensitive applications will poll. In my case it's both high throughput
> and latency sensitive.
Interesting. I assume you've measured that.
> [...]
> >looks for mmap/exec syscalls. Perhaps there could be a mode (a -D
> >setting?) for selecting kprobes rather than syscall-tracepoints to
> >catch those events.
>
> Why not trace just mmap and exec syscalls, rather than everything?
> Surely there's a static tracepoint for those.
Heh, in this case it's "surely not". :-) There exists only a
multiplexed system-call-entry and a system-call-exit pair of
tracepoints.
> I'd say defaulting to taking a spinlock on every syscall is going to
> cause anyone who's using more than a laptop a lot of pain.
There may well exist optimization opportunities that would benefit
syscall-saturated applications such as yours.
- FChE