Still waiting for swap prefetch [LWN.net]

Still waiting for swap prefetch

Posted Jul 26, 2007 15:15 UTC (Thu) by arjan (subscriber, #36785)
In reply to: Still waiting for swap prefetch by rsidd
Parent article: Still waiting for swap prefetch

> There's nothing wrong with python

... except that even a simple "hello world" seems to take 40 megabytes of memory. It's not about a few cpu cycles that kills you in performance, it's the enormous overhead that even simple programs get....

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Still waiting for swap prefetch

Posted Jul 26, 2007 17:11 UTC (Thu) by vmole (guest, #111) [Link]

That is so much crap.

$ cat hello.py
import time
print "hello, world"
time.sleep(30)

% python hello.py &
[1] 25243
hello, world
$ ps l -C python
F   UID   PID  PPID PRI  NI    VSZ   RSS WCHAN  STAT TTY        TIME COMMAND
0  1000 25446  2688  17   0   3844  2256 -      S    pts/0      0:00 python hello.py

So that's 2M resident, 4M virtual. And it exagerates a simple "hello world" program, because I had to import the time module for sleep() so I could run ps. Most of it is the interpeter itself, so multiple python programs don't actually take 4M each.

Python isn't perfect - what language is? But don't make stuff up, it just ruins your argument.

Still waiting for swap prefetch

Posted Jul 26, 2007 19:01 UTC (Thu) by nevyn (subscriber, #33129) [Link]

Let's try longer than 30 secs, eh?

% ps ax -o cmd:50,vsz,rss,stime | egrep '[p]ython'
/usr/bin/python -E /usr/sbin/setroubleshootd       808024 12104 Jul06
python /usr/share/system-config-printer/applet.py  232764  6436 Jul06
/usr/bin/python -E /usr/bin/sealert -s             411728 18524 Jul06
python /usr/libexec/revelation-applet --oaf-activa 458328 55056 Jul06
python /usr/lib64/gdesklets/gdesklets-daemon       453980 65768 Jul23
python ./hpssd.py                                  171220  1176 Jul11

...that's 2_536_044 KB VSZ and 159_064 KB RSS, and as you can see I've rebooted gdesklets recently (it was roughly double that, I think).

Plus I'm not running pupplet/yum-updatesd atm. And for instance "revelation-applet" is just a text entry box 95% of the time.

I appreciate that the huge VSZ numbers are (hopefully) mostly unused shared libs. etc. but half a GB is still a lot for the OS to manage for a text box, and 40+MB of RSS for a simple GUI is far from "so much crap".

For comparison my webserver uses two processes with a VSZ of about 12MB each and RSS of about 1MB each, and I'd prefer that to be smaller.

Still waiting for swap prefetch

Posted Jul 26, 2007 19:24 UTC (Thu) by vmole (guest, #111) [Link]

You said "a simple hello world" program, and that's what I tested. Comparing GUI programs to a webserver is irrelevant. What you've mostly demonstrated is that that GNOME/GTK is huge. Blaming that on Python doesn't seem to make sense. I'd bet a Perl implemenation of the same programs would be equally huge.