Inspired by #7065
When I'm testing some scripts or programs, they end up using more memory than anticipated. In that case, computer nearly halts due to swap space usage, and sometimes I have to press Magic SysRq+REISUB to reboot.
So, I was looking for a way to limit memory usage per script and found out that ulimit can limit memory. If you run it this way:
$ ulimit -v 1000000
.
$ scriptname
Then the new memory limit will be valid for that shell. I think changing the limit within a subshell is much more flexible and it won't interfere with your current shell ulimit settings.
note: -v 1000000 corresponds to approximately 1GB of RAM
In certain cases you mighy need to monitor the server load caused by certain process. For example HTTP, while stress testing apache using ab (apache benchmark) you may want to monitor the server status,load, # of spawned HTTP processes, # of established connections, # of connections in close wait state, apache memory footprint etc. Show Sample Output
For slow flash memory (cheap thumb drive), ext4 is the fastest stable file system for all use cases with no relevant exception:
http://www.linuxplanet.com/linuxplanet/tutorials/7208/1
Since we can usually dispense with the benefits of a journal for this type of storage, this is a way to achieve the least awful I/O-speed.
Disabling the journal for an existing ext4 partition can be achieved using
tune2fs -O ^has_journal /dev/sdXN
Note that it is often recommended to format removable flash media with ext2, due to the lack of a journal. ext4 has many advantages over ext2 even without the journal, with much better speed as one of the consequences. So the only usecase for ext2 would be compatibility with very old software.
smem is very clever, it keeps in mind shared memory in its calculations!!! http://www.selenic.com/smem/ Show Sample Output
How much memory is chrome sucking? Show Sample Output
To take information about the characteristics of the installed memory modules.
Show the maximum amount of memory that was needed by a process at any time. My use case: Having a long-running computation job on $BIG_COMPUTER and judging whether it will also run on $SMALL_COMPUTER. http://man7.org/linux/man-pages/man5/proc.5.html VmHWM: Peak resident set size ("high water mark") Show Sample Output
Sometimes top/htop don't give the fine-grained detail on memory usage you might need. Sum up the exact memory types you want
Top 10 Memory Processes (reduced output to applications and %usage only) Show Sample Output
It's like `prstat -t` under Solaris Show Sample Output
default stack size is 10M. This makes your multithread app filling rapidly your memory. on my PC I was able to create only 300thread with default stack size. Lower the default stack size to the one effectively used by your threads, let you create more. ex. putting 64k I was able to create more than 10.000threads. Obviously ...your thread shouldn't need more than 64k ram!!!
where - memory 256 assign 256 Mb RAM - acpi on enable ACPI (mandatory if you use Winfog 2000 - ioapic off disable the IO APIC. Not useful if you use one CPU (on virtual machine or a 32 bit operative system). As ACPI, this switch is mandatory for Winbug 2000 - pae on enable the Phisical Address Extension how to use more than 4Gb of RAM on x86 CPU - hwvirtex on enables hardware virtualization extensions for microprocessors that have this feature (which should be also enabled in the BIOS of the motherboard) - nestedpaging on allows part of the processes of memory management hardware are made directly
Restarts the XAPI service on the host, mostly used by Xen Center. It does not affect any running VMs, just the Xen client tools that may be connected. On my list as XAPI frustratingly keeps running out of memory and getting killed off. Show Sample Output
It grabs the PID's top resource users with $(ps -eo pid,pmem,pcpu| sort -k 3 -r|grep -v PID|head -10) The sort -k is sorting by the third field which would be CPU. Change this to 2 and it will sort accordingly. The rest of the command is just using diff to display the output of 2 commands side-by-side (-y flag) I chose some good ones for ps. pidstat comes with the sysstat package(sar, mpstat, iostat, pidstat) so if you don't have it, you should. I might should take off the timestamp... :| Show Sample Output
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