[sf-lug] ps -A | grep timidity

[Rick Moen]

Quoting Kristian Erik Hermansen (kristian.hermansen at gmail.com):
> On 9/26/07, Rick Moen <rick at linuxmafia.com> wrote:
> > There's a standard gotcha about the "top" utility:  It puts a machine
> > under significant load while running.  Picture a shared *ix host having
> > apparent performance problems:  A dozen logged-in users simultaneously
> > launch "top" and bring it to its knees.
> >
> > It happens.
> 
> Is true of shared hosts that utilize grsecurity patches?  In such a
> scenario, you will not be pulling info on any other processes than
> your own...

Let's look:  www.svlug.org has a grsecurity-patched kernel.  It's
certainly true that it does show you only your own processes:

rick at svlug:~$ top b n 1                 


 01:19:36 up 4 days, 18:10,  1 user,  load average: 0.34, 0.21, 0.19
3 processes: 2 sleeping, 1 running, 0 zombie, 0 stopped
CPU states:   0.9% user,   0.4% system,   0.0% nice,  98.7% idle
Mem:    513336K total,   508564K used,     4772K free,     9228K buffers
Swap:   530136K total,   310800K used,   219336K free,    17204K cached

  PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND
16587 rick       9   0  3012 2976  2820 S     0.0  0.5   0:00 sshd
16588 rick      11   0  2864 2864  2400 S     0.0  0.5   0:00 bash
16676 rick      11   0  1928 1928  1744 R     0.0  0.3   0:00 top
rick at svlug:~$


The top process itself still puts the system under nontrivial load, but 
I'm guesstimating that grsecurity makes the effect be somewhat lesser. 
As one point of comparison, FWIW, my Xubuntu-running iBook G3 has:

$ top b n 1 > /tmp/topoutput
$ less /tmp/topoutput

top - 01:22:43 up 1 day, 23:37,  3 users,  load average: 0.01, 0.05, 0.07
Tasks:  77 total,   3 running,  74 sleeping,   0 stopped,   0 zombie
Cpu(s):  6.5%us,  0.8%sy,  1.0%ni, 90.9%id,  0.5%wa,  0.3%hi,  0.0%si, 0.0%st
Mem:    385240k total,   381176k used,     4064k free,    56004k buffers
Swap:  1128632k total,      480k used,  1128152k free,    66552k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND            
17154 rick      15   0  2956 1184  924 R  3.9  0.3   0:00.03 top                
    1 root      16   0  2404  804  700 S  0.0  0.2   0:01.75 init               
    2 root      34  19     0    0    0 S  0.0  0.0   0:01.27 ksoftirqd/0        
    3 root      RT   0     0    0    0 S  0.0  0.0   0:00.00 watchdog/0         
    4 root      10  -5     0    0    0 S  0.0  0.0   0:05.21 events/0           
    5 root      10  -5     0    0    0 S  0.0  0.0   0:00.02 khelper            
    6 root      11  -5     0    0    0 S  0.0  0.0   0:00.00 kthread            
   25 root      10  -5     0    0    0 S  0.0  0.0   0:00.17 kblockd/0          
[...]