Shell – Equivalent command for “time“ for memory usage

memorymonitoringprocessshell

By using time we can easily get the information about how long a program run. I was wondering if there is any equivalent command I can use for memory usages? Like how much memory is allocated for this process, and how much is freed after it finishes? I am aware that I can use Valgrind but it is a bit too heavy-weight for me.

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> /usr/bin/time -v sleep 1
Command being timed: "sleep 1"
User time (seconds): 0.00
System time (seconds): 0.00
Percent of CPU this job got: 0%
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:01.01
Average shared text size (kbytes): 0
Average unshared data size (kbytes): 0
Average stack size (kbytes): 0
Average total size (kbytes): 0
Maximum resident set size (kbytes): 1820
Average resident set size (kbytes): 0
Major (requiring I/O) page faults: 1
Minor (reclaiming a frame) page faults: 91
Voluntary context switches: 2
Involuntary context switches: 2
Swaps: 0
File system inputs: 16
File system outputs: 0
Socket messages sent: 0
Socket messages received: 0
Signals delivered: 0
Page size (bytes): 4096
Exit status: 0

Related Solutions

RAM Usage – Measuring RAM Usage of a Program

You can use tstime to measure the highwater memory usage (RSS and virtual) of a process.

For example:

$ tstime date       
Tue Aug 16 21:35:02 CEST 2011

Exit status: 0

pid: 31169 (date) started: Tue Aug 16 21:35:02 2011
        real   0.017 s, user   0.000 s, sys   0.000s
        rss      888 kb, vm     9764 kb

It also supports a more easy to parse output mode (-t).

Linux – Does free() unmap the memory of a process

The C-library function free() can, but does not have to, return memory to the kernel.

Some implementations of malloc() move the boundary between "heap" and otherwise unused address space (the "system break") via the sbrk() system call, then dole out smaller pieces of those large allocations. Without getting every smaller piece de-allocated, free() can't really return the memory to the OS.

That same reason applies to malloc() implementations that don't use sbrk(2), but maybe use mmap("/dev/zero") or something.. I can't find a reference, but I seem to remember that one or another of the BSD's used mmap() that way to get pages of memory. Nevertheless, free() can't return a page to the operating system unless every sub-allocation is deallocated by the program.

Some malloc() implementations do return memory to the system: ChorusOS(?) apparently did. It's not clear if it moved the system break, or munmap()'ed pages.

Here's a paper about a memory allocator that improves performance by "aggressively giving up free pages to the virtual memory manager". Slide show for a talk about the allocator.

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Related Solutions

RAM Usage – Measuring RAM Usage of a Program

Linux – Does free() unmap the memory of a process

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