Re: [PACTH v2 0/3] Implement /proc/<pid>/totmaps

From: Robert Foss
Date: Mon Aug 22 2016 - 10:37:45 EST




On 2016-08-22 10:12 AM, 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)


$ ./smap_test &
pid:19658 nr_vma:65514

$ time awk '/^Rss/{rss+=$2} /^Pss/{pss+=$2} END {printf "rss:%d pss:%d\n", rss, pss}' /proc/19658/smaps
rss:263452 pss:262151

real 0m0.625s
user 0m0.404s
sys 0m0.216s

$ 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.

Thanks.