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jcpunk
n00b
Joined: 22 Jul 2003
Posts: 37
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 Posted: Wed Jan 14, 2004 6:47 pm Post subject: memory usage question |
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I am a little bit confused why 30% of my avalible memory is being used at boot when I am not running ANYTHING.
top reports:
| Code: |
Tasks: 23 total, 1 running, 22 sleeping, 0 stopped, 0 zombie
Cpu(s): 7.0% user, 4.4% system, 0.0% nice, 88.6% idle
Mem: 192152k total, 63864k used, 167888k free, 1868k buffers
Swap: 417672k total, 0k used, 417672k free, 15036k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1363 root 17 0 880 876 708 R 2.0 0.5 0:00.02 top
1 root 17 0 488 488 436 S 0.0 0.3 0:04.07 init
2 root 17 0 0 0 0 S 0.0 0.0 0:00.00 keventd
3 root 17 0 0 0 0 S 0.0 0.0 0:00.00 kapmd
4 root 36 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd_CPU0
5 root 23 0 0 0 0 S 0.0 0.0 0:00.00 kswapd
6 root 23 0 0 0 0 S 0.0 0.0 0:00.00 bdflush
7 root 17 0 0 0 0 S 0.0 0.0 0:00.00 kupdated
9 root 17 0 0 0 0 S 0.0 0.0 0:00.00 kreiserfsd
152 root 17 0 832 832 592 S 0.0 0.4 0:00.04 devfsd
356 root 17 0 0 0 0 S 0.0 0.0 0:00.00 khubd
826 root 17 0 648 648 548 S 0.0 0.3 0:00.01 metalog
827 root 17 0 532 532 468 S 0.0 0.3 0:00.00 metalog
1278 root 17 0 1392 1392 1256 S 0.0 0.7 0:00.86 sshd
1309 root 17 0 640 640 548 S 0.0 0.3 0:00.01 cron
1322 root 18 0 1132 1132 960 S 0.0 0.6 0:00.01 bash
1323 root 17 0 656 656 576 S 0.0 0.3 0:00.00 agetty
1324 root 17 0 656 656 576 S 0.0 0.3 0:00.01 agetty
1325 root 17 0 656 656 576 S 0.0 0.3 0:00.00 agetty
1326 root 17 0 656 656 576 S 0.0 0.3 0:00.00 agetty
1327 root 17 0 656 656 576 S 0.0 0.3 0:00.01 agetty
1328 root 17 0 1700 1700 1508 S 0.0 0.9 0:00.03 sshd
1330 root 18 0 1332 1332 1128 S 0.0 0.7 0:00.03 bash
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Does 43 Mb of RAM sound a little rediculous for what all is running and with only about 7 minutes of up time? or is that just me.
Anyone got any ideas where all that memory is going?
Last edited by jcpunk on Thu Jan 15, 2004 4:56 am; edited 1 time in total |
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jmz2
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Joined: 13 Jan 2004
Posts: 421
Location: Finland
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| Posted: Wed Jan 14, 2004 7:08 pm Post subject: |
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You seldom see free (as in not used) memory with Linux. The kernel uses much of the memory for filesystem caching -- this memory is freed to applications when they require memory.
If you're worried about memory usage, you can save a bit of it by not loading GLX modules in XFree, using zsh (or some other lightweight shell) as your default shell, and by picking applications which don't demand so much resources. |
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jcpunk
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Joined: 22 Jul 2003
Posts: 37
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| Posted: Wed Jan 14, 2004 11:10 pm Post subject: |
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While I agree that not loading parts of X (graphics acceleration and additional sessions) as well as using a lighter weight shell would save memory, I find it difficult to believe that my system which is not running X (so not loading GLX is already being taken care of, by not loading any part of X) and only running bash, sshd, and top should need to take up 43 Mb of memory.
Yes linux does buffer things but the quantity of memory being used seems rather rediculous for these programs and top records a buffer of only around 2Mb in use.
I am currently on a debian box running X, mozilla, xmms, gaim, and a few dozen other programs utilizing around 75Mb of RAM this seems much more reasonible, because SOMETHING is actually running on the computer. The gentool box has 4 processes that arnt recorded as sleeping when I run top, and none of them should be all that memory intensive. |
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jmz2
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Joined: 13 Jan 2004
Posts: 421
Location: Finland
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| Posted: Thu Jan 15, 2004 7:40 am Post subject: |
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| jcpunk wrote: | | While I agree that not loading parts of X (graphics acceleration and additional sessions) as well as using a lighter weight shell would save memory, I find it difficult to believe that my system which is not running X (so not loading GLX is already being taken care of, by not loading any part of X) and only running bash, sshd, and top should need to take up 43 Mb of memory....I am currently on a debian box running X, mozilla, xmms, gaim, and a few dozen other programs utilizing around 75Mb of RAM this seems much more reasonible, because SOMETHING is actually running on the computer. The gentool box has 4 processes that arnt recorded as sleeping when I run top, and none of them should be all that memory intensive. |
You missed the 18 MB of kernel caches. That plus the 2 MB of buffers totals 20 MB. So your kernel and programs are using 23 MB of memory. You can tune this by modularizing the kernel and loading modules as necessary. If you do not run X, then you may want to drop your graphics accelerator from the kernel configuration.
Metalog caches log files. If you choose some other system logger, you'd save a bit of memory there too. And if you want to really tune the system, you can change agettys to fgettys for example 
But the point here is, your system's memory usage is far from ridiculous. |
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jcpunk
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Joined: 22 Jul 2003
Posts: 37
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| Posted: Thu Jan 15, 2004 8:44 pm Post subject: |
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| cool, thanks for the info... the memory usage still seems a bit high, but at least there is an explination. |
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jmz2
Guru
Joined: 13 Jan 2004
Posts: 421
Location: Finland
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| Posted: Thu Jan 15, 2004 8:55 pm Post subject: |
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| For your amusement, you can check out other memory footprint reducing options, like those present in the 2.6 kernel (remove kernel features, somewhere in menuconfig, don't remember where it was), and dietlibc. Dietlibc is in Portage. I don't recommend trying them out unless you know what you're doing (or want to experiment). |
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