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#1 2013-03-14 00:02:06
- archnet
- Member
- Registered: 2011-05-09
- Posts: 42
Where is all my RAM going?
A recent thread (https://bbs.archlinux.org/viewtopic.php?id=118050) got me curious. So, I booted into a basic console session with bare minimums. Here is the result of top showing the memory statistics of only those processes that top showed had a non-zero memory usage (I sorted by memory). The values are 1) VIRT, 2) RES, and 3) SHR.
3978032 total, 151816 used, 3826216 free, 10468 buffers, 54048 cached
systemd-journal 306m 12m 12m
systemd 32532 3112 1880
nvi 17672 3096 2056
systemd-udevd 31632 2024 1088
login 63012 1916 1472
login 63012 1916 1472
systemd-logind 26088 1608 1308
top 13388 1440 1040
wpa_supplicant 32316 1356 804
dbus-daemon 19368 1304 1076
agetty 8148 820 700
agetty 8148 820 700
dash 4312 716 588
dash 4312 716 588
wpa_actiond 4216 480 392
dhcpcd 8568 344 200Immediately following logging this information, I ran free, which gave me this information.
total used free shared buffers cached
Mem: 3978032 150436 3827596 0 10508 54052
-/+ buffers/cache: 85876 3892156
Swap: 0 0 0That's almost 84 megabytes for doing just about nothing!!! One thing that really stands out is how much of a resource hog systemd is. Why did Arch move away from the lean & mean init machine?!
Now, if you just naively add up all the RES values, they only add up to 33956K. That's only 33 megabytes. So somewhere there's 50 megabytes being eaten by something that isn't being reported.
Anyone know where my missing 50 megabytes may be found?
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#2 2013-03-14 00:24:07
- jasonwryan
- Anarchist
- From: .nz
- Registered: 2009-05-09
- Posts: 30,426
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Re: Where is all my RAM going?
One thing that really stands out is how much of a resource hog systemd is. Why did Arch move away from the lean & mean init machine?!
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#3 2013-03-14 00:27:52
- archnet
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- Registered: 2011-05-09
- Posts: 42
Re: Where is all my RAM going?
archnet wrote:One thing that really stands out is how much of a resource hog systemd is. Why did Arch move away from the lean & mean init machine?!
Yeah, I've read the developers reasons. I still don't buy into them, though. But, that's neither here nor there for the purpose of basic question I pose here, though. My mention of it was more-or-less of an ugh! moment. If I want to delve further into that discussion, I'll start another thread devoted to it.
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#4 2013-03-14 00:32:39
- jasonwryan
- Anarchist
- From: .nz
- Registered: 2009-05-09
- Posts: 30,426
- Website
Re: Where is all my RAM going?
jasonwryan wrote:archnet wrote:One thing that really stands out is how much of a resource hog systemd is. Why did Arch move away from the lean & mean init machine?!
Yeah, I've read the developers reasons. I still don't buy into them, though. But, that's neither here nor there for the purpose of basic question I pose here, though. My mention of it was more-or-less of an ugh! moment. If I want to delve further into that discussion, I'll start another thread devoted to it.
Don't do that: this "question" has been asked many times, and the answer is provided in the post I linked to.
Furthermore, questioning or discussing the methods used by the Arch Linux development team will be monitored closely and locked if deemed unhelpful and/or unproductive. Harsh, unproductive criticism is also uncalled for.
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#5 2013-03-14 01:00:52
- lucke
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- From: Poland
- Registered: 2004-11-30
- Posts: 4,018
Re: Where is all my RAM going?
systemd doesn't eat much RAM here.
PID User Command Swap USS PSS RSS
137 root /usr/lib/systemd/systemd-ud 428.0K 4.0K 9.0K 284.0K
334 root /usr/lib/systemd/systemd-lo 208.0K 76.0K 87.0K 560.0K
138 root /usr/lib/systemd/systemd-jo 224.0K 96.0K 104.0K 444.0K
1 root /bin/systemd 772.0K 540.0K 554.0K 1.0Msyslog, consolekit, udev and regular init (all replaced by systemd) were also using memory.
4311 root /usr/sbin/console-kit-daemo 0 1.2M 1.6M 3.4M
4714 root /usr/sbin/syslog-ng -F 0 1.5M 1.8M 3.2MLast edited by lucke (2013-03-14 01:10:32)
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#6 2013-03-14 07:29:03
- Awebb
- Member
- Registered: 2010-05-06
- Posts: 6,688
Re: Where is all my RAM going?
Those 50MB are found in your lack of comprehension of RAM handling in Linux. I will demonstrate.
After Killing KDM:
$ free -m
total used free shared buffers cached
Mem: 2010 925 1085 0 75 742
-/+ buffers/cache: 107 1902
Swap: 2047 0 2047After stopping everything in multi.user.target:
# systemctl stop avahi-daemon.socket cronie.service cups.socket ftpd.service mpd.service NetworkManager.service sshd.service syslog-ng.service
$ free -m
total used free shared buffers cached
Mem: 2010 906 1104 0 75 743
-/+ buffers/cache: 87 1923
Swap: 2047 0 2047After disabling everything in multi.user.target and rebooting:
$ free -m
total used free shared buffers cached
Mem: 2010 76 1934 0 15 25
-/+ buffers/cache: 34 1975
Swap: 2047 0 2047Similar phenomena can be observed even without systemd. This is neither pleasant nor particularly useful, but it is the way of the penguin. The only way to really know, how much free ram you have, is redirecting /dev/urandom to both, a file in /tmp as well as /dev/shm, wait for them to terminate and add the sizes. Whatever you do, don't be that kind of a dick and warm over last years trollbait, just because you don't understand the system.
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#7 2013-03-14 07:58:44
- elkoraco
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- Registered: 2013-02-18
- Posts: 140
Re: Where is all my RAM going?
That's almost 84 megabytes for doing just about nothing!!!
How dare they? A whole 84 MB!
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#8 2013-03-14 08:28:19
- Awebb
- Member
- Registered: 2010-05-06
- Posts: 6,688
Re: Where is all my RAM going?
archnet wrote:That's almost 84 megabytes for doing just about nothing!!!
How dare they? A whole 84 MB!
Eh, that's what Crunchbang used to eat in a full desktop :-D
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