Erik de Castro Lopo wrote:
Carlo,
In case you missed it, pay particular attention to this post from
Matt Palmer. In particular these bits.
Ye I've read this. With regards to his comment regarding a large process
exiting, no, my app has been the only one running that whole day. It is
strange at why Linux is doing that. Actually, I do agree with Matt that
most likely Linux is swapping that's why I've been searching for some
articles on high-memory processes on Linux. I've seen a few
techno-babbling on some lists about 2.4 vs 2.6 kernels. RHEL3 still uses
2.4. I might arrange for RHEL4 to be installed instead.
Also, when I get around it I'll install dstat and perform some swap file
testing by tomorrow.
Everyone in this list has been incredibly helpful.
Cheers,
Carlo
Matthew Palmer wrote:
What I suspect might be happening (and which is supported by the top output
you gave; see below) is that you're hitting swap and the system is grinding
to a halt. What's really odd is that you've still got umpteen GB of free
memory -- I'd expect the system to use that before hitting swap. Maybe your
top output is anomalous, though.
<snip>
Swap evidence:
CPU states: cpu user nice system irq softirq iowait idle
total 0.4% 0.0% 0.2% 0.0% 0.0% 12.1% 87.0%
cpu00 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0%
cpu01 0.9% 0.0% 0.0% 0.0% 0.0% 0.0% 99.0%
cpu02 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0%
cpu03 0.0% 0.0% 1.9% 0.0% 0.0% 0.0% 98.0%
cpu04 2.9% 0.0% 0.0% 0.0% 0.0% 97.0% 0.0%
^^^^^
Massive iowait is a very common sign of massive swapping. It's not the only
possible cause, but it's certainly the most common IME...
Mem: 9879976k av, 2391196k used, 7488780k free, 0k shrd, 35592k
buff
2009064k actv, 134928k in_d, 83160k in_c
Swap: 2044072k av, 1022036k used, 1022036k free 246204k
... especially when you're 1G into hock.
The odd bit is the 7.4GB of free memory that's sitting there. I can't
imagine why the system would be shoving stuff into swap when there was large
gobs of available memory, but it's possible that a *very* large process just
terminated when you snapped this output. I'd look at top output more
closely. There's also various options to sar (-R, -W) that'll show you how
quickly pages are being brought in and out.
Erik
--
Carlo Sogono
Software Engineer
Protocom Technology Pty Ltd
Level 4, 447 Kent St
Sydney, NSW 2000
AUSTRALIA
Website : http://www.protocomtech.com.au
Email : [EMAIL PROTECTED]
Phone : +61 2 9264 1316
Fax : +61 2 9264 1915
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