Hi Mikko, Patrick,
On 22/10/2013 10:39, Patrick Ohly wrote:
On Tue, 2013-10-22 at 10:35 +0300, Ylinen, Mikko wrote:
Hi Stephane,
On Mon, Oct 21, 2013 at 5:56 PM, Stéphane Desneux
<[email protected]> wrote:
I saw in the launchpad code that the preloading uses dlopen()
with the flag RTLD_NOW: this forces to load all unresolved
symbols, thus the whole library tree.
As the WRT launchpad executes this dlopen() for all binaries
listed in /usr/share/aul/preload*.txt, this leads to loading
nearly 200 libs:
# for x in $( cat /usr/share/aul/preload*.txt); do ldd $x;
done | awk '{print $1}' | sort | uniq | wc -l
202
This is confirmed by reading the list of mapped files for the
process:
# readlink /proc/$(pgrep wrt_launchpad)/map_files/* | grep .so
| sort | uniq | wc -l
205
Just out of curiosity: will the WRT launchpad daemon startup time
improve if you disable libs dlopen()?
This is important for the system startup time.
Mikko: the 200+ libs are opened and mmaped but this doesn't take much
time. On my target device (lenovo X230: core i5 IvyBridge), the first
start of wrt_launchpad_daemon (cold boot) from command line takes less
than 500ms.
A restart of the wrt launchpad takes ~130ms and no disk IO is observed
=> the first time, 370ms are spent on disk IOs.
Perhaps also worth investigating: is RTLD_NOW necessary or can RTLD_LAZY
be used?
Stéphane said that it causes loading "the while library tree", which is
a bit misleading. The same set of libraries should be loaded with and
without it. The difference is that symbol resolution happens for
everything during loading when RTLD_NOW is used, while it gets deferred
for functions until they are actually used with RTLD_LAZY.
Using ltrace (see attached log), I could see that all calls are made
with RTLD_NOW (flag & 0x2 == 2 in dlopen calls)
This is a trace with explicit calls to dlopen() in the launchpad. To be
compared with a strace, where all dependent libs are loaded in turn
(this leads to the 200+ libs mapped).
Symbol resolution can be expensive, so startup time might benefit from
not doing it immediately. Functions that never get called don't need to
be resolved at all.
On the other hand, because functions get called in the forked processes,
this work then needs to be done over and over again, which negates the
purpose of preloading somewhat.
There's a process pool implemented in wrt launchpad, but it seems
disabled on recent images (or I'm misunderstanding the signification of
'process pool'). In package wrt=0.8.198.3-12.17, the
/etc/profile.d/wrt_env.sh contains 'export WRT_PROCESS_POOL_DISABLE=ON'.
Even by removing this export, the launchpad doesn't prefork any process.
Strange... I'll check why it's disabled.
There may be a way to get the best of both worlds: during startup, use
RTLD_LAZY. Then sometime later, call dlopen() again for the same modules
with RTLD_NOW. According to the dlopen() man page, that has the effect
of retroactively resolving all symbols without actually loading the
module again.
Something else to watch our for is that switching between
RTLD_LAZY/RTLD_NOW may also affect which symbols a function call is
bound to. This is probably unlikely, but who knows...
Another semantic difference is that a module fails to load with RTLD_NOW
if any of its symbols cannot be resolved. With RTLD_LAZY, it gets loaded
and a runtime error occurs when calling an unresolvable method.
This is definitely something to investigate.
Kind regards,
--
Stéphane Desneux
Intel OTC - Vannes/FR
__libc_start_main(0x403230, 2, 0x7fffb7029d28, 0x408c90 <unfinished ...>
getenv("WRT_PROCESS_POOL_DISABLE")
= nil <0.000141>
signal(0, 0)
= 0xffffffffffffffff <0.000110>
signal(SIGHUP, 0)
= 0 <0.000078>
signal(SIGINT, 0)
= 0 <0.000075>
signal(SIGTRAP, 0)
= 0 <0.000075>
signal(SIGKILL, 0)
= 0xffffffffffffffff <0.000076>
signal(SIGUSR1, 0)
= 0 <0.000075>
signal(SIGUSR2, 0)
= 0 <0.000099>
signal(SIGALRM, 0)
= 0 <0.000094>
signal(SIGTERM, 0)
= 0 <0.000088>
signal(SIGSTKFLT, 0)
= 0 <0.000087>
signal(SIGCHLD, 0)
= 0 <0.000087>
signal(SIGCONT, 0)
= 0 <0.000088>
signal(SIGSTOP, 0)
= 0xffffffffffffffff <0.000087>
signal(SIGTSTP, 0)
= 0 <0.000087>
signal(SIGTTIN, 0)
= 0 <0.000087>
signal(SIGTTOU, 0)
= 0 <0.000096>
signal(SIGURG, 0)
= 0 <0.000088>
signal(SIGXCPU, 0)
= 0 <0.000088>
signal(SIGXFSZ, 0)
= 0 <0.000088>
signal(SIGVTALRM, 0)
= 0 <0.000087>
signal(SIGPROF, 0)
= 0 <0.000087>
signal(SIGWINCH, 0)
= 0 <0.000087>
signal(SIGIO, 0)
= 0 <0.000087>
signal(SIGPWR, 0)
= 0 <0.000087>
signal(SIGSYS, 0)
= 0 <0.000092>
signal(SIGRTMIN_0, 0)
= 0xffffffffffffffff <0.000070>
signal(SIGRTMIN_1, 0)
= 0xffffffffffffffff <0.000070>
signal(SIGRTMIN_2, 0)
= 0 <0.000087>
signal(SIGRTMIN_3, 0)
= 0 <0.000087>
signal(SIGRTMIN_4, 0)
= 0 <0.000087>
signal(SIGRTMIN_5, 0)
= 0 <0.000087>
signal(SIGRTMIN_6, 0)
= 0 <0.000087>
signal(SIGRTMIN_7, 0)
= 0 <0.000088>
signal(SIGRTMIN_8, 0)
= 0 <0.000095>
signal(SIGRTMIN_9, 0)
= 0 <0.000088>
signal(SIGRTMIN_10, 0)
= 0 <0.000087>
signal(SIGRTMIN_11, 0)
= 0 <0.000089>
signal(SIGRTMIN_12, 0)
= 0 <0.000088>
signal(SIGRTMIN_13, 0)
= 0 <0.000088>
signal(SIGRTMIN_14, 0)
= 0 <0.000087>
signal(SIGRTMIN_15, 0)
= 0 <0.000088>
signal(SIGRTMIN_16, 0)
= 0 <0.000087>
signal(SIGRTMIN_17, 0)
= 0 <0.000092>
signal(SIGRTMIN_18, 0)
= 0 <0.000088>
signal(SIGRTMIN_19, 0)
= 0 <0.000087>
signal(SIGRTMIN_20, 0)
= 0 <0.000089>
signal(SIGRTMIN_21, 0)
= 0 <0.000088>
signal(SIGRTMIN_22, 0)
= 0 <0.000087>
signal(SIGRTMIN_23, 0)
= 0 <0.000089>
signal(SIGRTMIN_24, 0)
= 0 <0.000088>
signal(SIGRTMIN_25, 0)
= 0 <0.000088>
signal(SIGRTMIN_26, 0)
= 0 <0.000089>
signal(SIGRTMIN_27, 0)
= 0 <0.000088>
signal(SIGRTMIN_28, 0)
= 0 <0.000088>
signal(SIGRTMIN_29, 0)
= 0 <0.000088>
signal(SIGRTMIN_30, 0)
= 0 <0.000089>
signal(SIGRTMIN_31, 0)
= 0 <0.000088>
signal(64, 0)
= 0 <0.000088>
getpid()
= 24316 <0.000068>
__snprintf_chk(0x7fffb70299a0, 128, 1, 128)
= 19 <0.000093>
open("/proc/24316/cmdline", 0, 026700514663)
= 3 <0.000125>
read(3, "/usr/bin/wrt_launchpad_daemon", 127)
= 127 <0.000094>
close(3)
= 0 <0.000086>
__strdup(0x7fffb70299a0, 0x7fffb70299a2, 127, 5)
= 0x1632030 <0.000076>
__dlog_print(0, 3, 0x40a014, 0x409b30)
= 0 <0.000187>
umask(00)
= 022 <0.000084>
mkdir("/tmp/alaunch", 01777)
= -1 <0.000103>
umask(022)
= 00 <0.000082>
socket(1, 524289, 0)
= 6 <0.000095>
__snprintf_chk(0x7fffb7029932, 108, 1, 108)
= 15 <0.000076>
unlink("/tmp/alaunch/-3")
= 0 <0.000110>
getuid()
= 0 <0.000080>
smack_fsetlabel(6, 0x408d75, 5, -1)
= 0 <0.000096>
smack_fsetlabel(6, 0x408d77, 4, -1)
= 0 <0.000090>
bind(6, 0x7fffb7029930, 110, -1)
= 0 <0.000100>
chmod("/tmp/alaunch/-3", 0777)
= 0 <0.000114>
setsockopt(6, 1, 7, 0x7fffb702992c)
= 0 <0.000091>
setsockopt(6, 1, 8, 0x7fffb702992c)
= 0 <0.000088>
listen(6, 10, 8, -1)
= 0 <0.000089>
strlen("/usr/bin/wrt_launchpad_daemon")
= 29 <0.000102>
strlen(" "...)
= 201 <0.000178>
__dlog_print(0, 3, 0x40a014, 0x409b78)
= 0 <0.000070>
fopen("/usr/share/aul/preload_list.txt", "rt")
= 0x1632060 <0.000135>
fgets("/usr/lib64/libappcore-efl.so.1\n", 128, 0x1632060)
= 0x7fffb7029b70 <0.000145>
strnlen(0x7fffb7029b70, 128, 0x1632140, 0)
= 31 <0.000072>
calloc(1, 24)
= 0x16322a0 <0.000068>
dlopen("/usr/lib64/libappcore-efl.so.1", 2)
= 0x1632320 <0.059413>
__dlog_print(0, 3, 0x40a014, 0x409bc0)
= 0 <0.000104>
dlsym(0x1632320, "elm_quicklaunch_init")
= 0x7fbc88d4d150 <0.000100>
__dlog_print(0, 3, 0x40a014, 0x409be8)
= 0 <0.000060>
dlsym(0x1632320, "elm_quicklaunch_shutdown")
= 0x7fbc88d4db70 <0.000085>
__dlog_print(0, 3, 0x40a014, 0x409c18)
= 0 <0.000059>
g_slist_prepend(0, 0x16322a0, 0, 0x409c18)
= 0x165a920 <0.000061>
fgets("/usr/lib64/libappcore-common.so."..., 128, 0x1632060)
= 0x7fffb7029b70 <0.000055>
strnlen(0x7fffb7029b70, 128, 0x1632140, 0)
= 34 <0.000060>
calloc(1, 24)
= 0x165c4c0 <0.000056>
dlopen("/usr/lib64/libappcore-common.so."..., 2)
= 0x1634130 <0.000324>
__dlog_print(0, 3, 0x40a014, 0x409bc0)
= 0 <0.000059>
dlsym(0x1634130, "elm_quicklaunch_init")
= 0 <0.000082>
g_slist_prepend(0x165a920, 0x165c4c0, 0x7fbc8bc0e908, 1)
= 0x165a930 <0.000060>
fgets("/usr/lib64/ecore/immodules/libis"..., 128, 0x1632060)
= 0x7fffb7029b70 <0.000055>
strnlen(0x7fffb7029b70, 128, 0x1632140, 0)
= 48 <0.000059>
calloc(1, 24)
= 0x163e660 <0.000056>
dlopen("/usr/lib64/ecore/immodules/libis"..., 2)
= 0 <0.000120>
free(0x163e660)
= <void> <0.000056>
fgets("/usr/lib64/osp/libosp-appfw.so\n", 128, 0x1632060)
= 0x7fffb7029b70 <0.000053>
strnlen(0x7fffb7029b70, 128, 0x1632140, 0)
= 31 <0.000059>
calloc(1, 24)
= 0x163e660 <0.000056>
dlopen("/usr/lib64/osp/libosp-appfw.so", 2)
= 0 <0.000108>
free(0x163e660)
= <void> <0.000054>
fgets("/usr/lib64/osp/libosp-uifw.so\n", 128, 0x1632060)
= 0x7fffb7029b70 <0.000055>
strnlen(0x7fffb7029b70, 128, 0x1632140, 0)
= 30 <0.000060>
calloc(1, 24)
= 0x163e660 <0.000056>
dlopen("/usr/lib64/osp/libosp-uifw.so", 2)
= 0 <0.000106>
free(0x163e660)
= <void> <0.000054>
fgets("/usr/lib64/osp/libosp-uifw.so", 128, 0x1632060)
= 0 <0.000066>
fclose(0x1632060)
= 0 <0.000087>
__cxa_atexit(0x405b50, 0, 0, 0xfbad000c)
= 0 <0.000065>
fopen("/usr/share/aul/preload_list_wrt."..., "rt")
= 0x1632060 <0.000111>
fgets("/usr/bin/wrt-client\n", 128, 0x1632060)
= 0x7fffb7029b70 <0.000093>
strnlen(0x7fffb7029b70, 128, 0x1632140, 0)
= 20 <0.000059>
dlopen("/usr/bin/wrt-client", 258)
= 0x165c860 <0.174964>
realloc(0, 80)
= 0x169f120 <0.000071>
__dlog_print(0, 3, 0x40a014, 0x409bc0)
= 0 <0.000065>
fgets("/usr/lib64/libwrt-injected-bundl"..., 128, 0x1632060)
= 0x7fffb7029b70 <0.000058>
strnlen(0x7fffb7029b70, 128, 0x1632140, 0)
= 37 <0.000063>
dlopen("/usr/lib64/libwrt-injected-bundl"..., 258)
= 0x169f1b0 <0.077871>
__dlog_print(0, 3, 0x40a014, 0x409bc0)
= 0 <0.000077>
fgets("/usr/lib64/wrt-plugins/w3c-widge"..., 128, 0x1632060)
= 0x7fffb7029b70 <0.000058>
strnlen(0x7fffb7029b70, 128, 0x1632140, 0)
= 83 <0.000112>
dlopen("/usr/lib64/wrt-plugins/w3c-widge"..., 258)
= 0x16a83c0 <0.072298>
__dlog_print(0, 3, 0x40a014, 0x409bc0)
= 0 <0.000089>
fgets("/usr/lib64/wrt-plugins/tizen-tiz"..., 128, 0x1632060)
= 0x7fffb7029b70 <0.000060>
strnlen(0x7fffb7029b70, 128, 0x1632140, 0)
= 65 <0.000065>
dlopen("/usr/lib64/wrt-plugins/tizen-tiz"..., 258)
= 0x169eb20 <0.075723>
__dlog_print(0, 3, 0x40a014, 0x409bc0)
= 0 <0.000084>
fgets("/usr/lib64/wrt-plugins/tizen-tiz"..., 128, 0x1632060)
= 0 <0.000071>
fclose(0x1632060)
= 0 <0.000085>
fopen("/usr/share/aul/preexec_list.txt", "rt")
= 0x1632060 <0.000118>
__dlog_print(0, 3, 0x40a014, 0x40a369)
= 0 <0.000060>
fgets("#preexec configuration\n", 128, 0x1632060)
= 0x7fffb7029b70 <0.000094>
fgets("##usage##\n", 128, 0x1632060)
= 0x7fffb7029b70 <0.000055>
fgets("#[type]: [preexec so path], [pre"..., 128, 0x1632060)
= 0x7fffb7029b70 <0.000054>
fgets("tpk: /usr/lib64/libosp-env-confi"..., 128, 0x1632060)
= 0x7fffb7029b70 <0.000055>
__strtok_r(0x7fffb7029b70, 0x40a385, 0x7fffb7029ad0, 0)
= 0x7fffb7029b70 <0.000062>
__strtok_r(0, 0x40a38d, 0x7fffb7029ad0, 0x7fffb7029b74)
= 0x7fffb7029b75 <0.000059>
__strtok_r(0, 0x40a38d, 0x7fffb7029ad0, 0x7fffb7029b95)
= 0x7fffb7029b96 <0.000059>
calloc(1, 32)
= 0x16b4270 <0.000056>
dlopen("/usr/lib64/libosp-env-config.so", 2)
= 0 <0.000145>
free(0x16b4270)
= <void> <0.000055>
fgets("tpk", 128, 0x1632060)
= 0 <0.000066>
fclose(0x1632060)
= 0 <0.000082>
socket(1, 524289, 0)
= 7 <0.000078>
__snprintf_chk(0x7fffb70299a2, 108, 1, 108)
= 28 <0.000060>
unlink("/tmp/wrt_process_pool_server")
= 0 <0.000103>
__dlog_print(0, 3, 0x408d51, 0x40aa45)
= 0 <0.000059>
bind(7, 0x7fffb70299a0, 110, 0x40aa45)
= 0 <0.000088>
__dlog_print(0, 3, 0x408d51, 0x40aa5d)
= 0 <0.000065>
chmod("/tmp/wrt_process_pool_server", 0777)
= 0 <0.000120>
__dlog_print(0, 3, 0x408d51, 0x40aa8f)
= 0 <0.000063>
listen(7, 10, 0, 0x40aa8f)
= 0 <0.000075>
__dlog_print(0, 3, 0x408d51, 0x40a930)
= 0 <0.000059>
time(0)
= 1382437786 <0.000056>
time(0)
= 1382437786 <0.000053>
time(0)
= 1382437786 <0.000052>
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