Linux memory

# pmap 1
1: /usr/lib/systemd/systemd --system --deserialize 18
0000561240af8000 1412K r-x-- systemd
0000561240e58000 140K r---- systemd
0000561240e7b000 4K rw--- systemd
00005612418e9000 1856K rw--- [ anon ]
00007f5534000000 164K rw--- [ anon ]
00007f5534029000 65372K ----- [ anon ]
00007f553c000000 164K rw--- [ anon ] used heap for thread *
00007f553c029000 65372K ----- [ anon ] unused heap for thread * (used + unused = 64M)
00007f5540dc7000 4K ----- [ anon ]
00007f5540dc8000 8192K rw--- [ anon ] stack for thread x
00007f55415c8000 4K ----- [ anon ]
00007f55415c9000 8192K rw--- [ anon ] stack for thread y
00007f5541dc9000 4K ----- [ anon ]
00007f5541dca000 8192K rw--- [ anon ]
00007f55425ca000 16K r-x-- libuuid.so.1.3.0

pmap就是将/proc/$pid/smaps内容打印出来。

each thread stack size configuration can be found:

# ulimit -a
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 256778

strace命令可以发现虚拟内存的堆分配：

#strace -f -ff -tt -e trace=all -o ~/systemcall.log <pid>

-f Trace child processes as they are created by currently traced processes as a result of the fork(2), vfork(2) and clone(2) system calls.

-ff If the -o filename option is in effect, each processes trace is written to filename.pid

#cat systemcall.log

....

mmap(0x7efcbc000000, 67108864, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x7efcb4000000

.....

Dump memory：

dd if=/proc/12987/mem bs=1 skip=$((0x7f521effe000)) count=$((4*1024)) status=none

dd if=/proc/6744/mem bs=1 skip=$((0x01bb7000)) count=$((0x01c3e000-0x01bb7000)) status=none | strings | less

valgrind