On Mon 22-08-16 23:12:41, Minchan Kim wrote:
> On Mon, Aug 22, 2016 at 09:40:52AM +0200, Michal Hocko wrote:
> > On Mon 22-08-16 09:07:45, Minchan Kim wrote:
> > [...]
> > > #!/bin/sh
> > > ./smap_test &
> > > pid=$!
> > >
> > > for i in $(seq 25)
> > > do
> > > awk '/^Rss/{rss+=$2} /^Pss/{pss+=$2} END {}' \
> > > /proc/$pid/smaps
> > > done
> > > kill $pid
> > >
> > > root@bbox:/home/barrios/test/smap# time ./s.sh
> > > pid:21973
> > >
> > > real 0m17.812s
> > > user 0m12.612s
> > > sys 0m5.187s
> >
> > retested on the bare metal (x86_64 - 2CPUs)
> > Command being timed: "sh s.sh"
> > User time (seconds): 0.00
> > System time (seconds): 18.08
> > Percent of CPU this job got: 98%
> > Elapsed (wall clock) time (h:mm:ss or m:ss): 0:18.29
> >
> > multiple runs are quite consistent in those numbers. I am running with
> > $ awk --version
> > GNU Awk 4.1.3, API: 1.1 (GNU MPFR 3.1.4, GNU MP 6.1.0)
> >
> > > > like a problem we are not able to address. And I would even argue that
> > > > we want to address it in a generic way as much as possible.
> > >
> > > Sure. What solution do you think as generic way?
> >
> > either optimize seq_printf or replace it with something faster.
>
> If it's real culprit, I agree. However, I tested your test program on
> my 2 x86 machines and my friend's machine.
>
> Ubuntu, Fedora, Arch
>
> They have awk 4.0.1 and 4.1.3.
>
> Result are same. Userspace speand more times I mentioned.
>
> [root@blaptop smap_test]# time awk '/^Rss/{rss+=$2} /^Pss/{pss+=$2} END {printf "rss:%d pss:%d\n", rss, pss}' /proc/3552/smaps
> rss:263484 pss:262188
>
> real 0m0.770s
> user 0m0.574s
> sys 0m0.197s
>
> I will attach my test progrma source.
> I hope you guys test and repost the result because it's the key for direction
> of patchset.
Hmm, this is really interesting. I have checked a different machine and
it shows different results. Same code, slightly different version of awk
(4.1.0) and the results are different
Command being timed: "awk /^Rss/{rss+=$2} /^Pss/{pss+=$2} END {printf "rss:%d pss:%d\n", rss, pss} /proc/48925/smaps"
User time (seconds): 0.43
System time (seconds): 0.27
I have no idea why those numbers are so different on my laptop
yet. It surely looks suspicious. I will try to debug this further
tomorrow. Anyway, the performance is just one side of the problem. I
have tried to express my concerns about a single exported pss value in
other email. Please try to step back and think about how useful is this
information without the knowing which resource we are talking about.
--
Michal Hocko
SUSE Labs
--
To unsubscribe from this list: send the line "unsubscribe linux-doc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
