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

[Robert Foss <robert.foss@collabora.com>]

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.
>