search for: sem_wait

...mething regarding synchronization objects. I have a multithreaded C++ program in which I use semaphores (POSIX version) for synchronization. I was interested in using DTrace to figure out the total time for which each thread in my application sleeps, blocked on a semaphore, i.e., as a result of sem_wait() call. In order to measure this, I wrote a script with sched:::sleep and sched:wakeup probes enabled, as shown below: sched:::sleep /execname == "myexecname"/ { ustack(); bedtime[curlwpsinfo->pr_addr,curlwpsinfo->pr_stype] = walltimestamp; } sched:::wakeup /be...

According to the man pages for sem_wait, etc., POSIX semaphores are available in Linux 2.6 (with the right NTPL threading in glibc). However, I have a program that compiles just fine but won't link because it can't find the library for the semaphore operations. What am I missing? I ran a find and grep through all the libc'...

...ined reference to `sem_init' /lib64/libcom_err.a(error_message.o): In function `fini_et_lock': error_message.c:(.text+0x1cc): undefined reference to `sem_destroy' /lib64/libcom_err.a(error_message.o): In function `et_list_lock': error_message.c:(.text+0x1ff): undefined reference to `sem_wait' /lib64/libcom_err.a(error_message.o): In function `et_list_unlock': error_message.c:(.text+0x228): undefined reference to `sem_post' collect2: ld returned 1 exit status make[1]: *** [fsck.ocfs2] Error 1 make[1]: Leaving directory `/tmp/SBo/ocfs2-tools-1.6.3/fsck.ocfs2' make: *** [f...

.../et/../../../lib/et/error_message.c:95: undefined reference to `sem_post' /usr/lib/gcc/x86_64-unknown-linux-gnu/4.4.1/../../../../lib/libcom_err.a(error_message.o): In function `et_list_lock': /sources/e2fsprogs-1.41.9/build/lib/et/../../../lib/et/error_message.c:85: undefined reference to `sem_wait' collect2: ld returned 1 exit status make[1]: *** [fsck.ocfs2] Error 1 make[1]: Leaving directory `/root/localdir/fsck.ocfs2' make: *** [fsck.ocfs2] Error 2 -------------------------------------------------------------------------------------------------------------------------- Anyone have...

.../et/../../../lib/et/error_message.c:95: undefined reference to `sem_post' /usr/lib/gcc/x86_64-unknown-linux-gnu/4.4.1/../../../../lib/libcom_err.a(error_message.o): In function `et_list_lock': /sources/e2fsprogs-1.41.9/build/lib/et/../../../lib/et/error_message.c:85: undefined reference to `sem_wait' collect2: ld returned 1 exit status make[1]: *** [fsck.ocfs2] Error 1 make[1]: Leaving directory `/root/localdir/fsck.ocfs2' make: *** [fsck.ocfs2] Error 2 -------------------------------------------------------------------------------------------------------------------------- Anyone have...

...config.log' for more details > > [ato at f16 febootstrap-3.12]$ gcc -std=gnu99 -o conftest -g -O2 conftest.c -lcom_err > /usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../lib64/libcom_err.a(error_message.o): In function `et_list_lock': > (.text+0x18d): undefined reference to `sem_wait' > /usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../lib64/libcom_err.a(error_message.o): In function `et_list_unlock': > (.text+0x1b6): undefined reference to `sem_post' > /usr/lib/gcc/x86_64-redhat-linux/4.6.2/../../../../lib64/libcom_err.a(error_message.o): In function `set...

...undefined reference to `sem_destroy' /lib/libcom_err.a(error_message.o): In function `setup_et_lock': error_message.c:(.text+0x6e): undefined reference to `sem_init' /lib/libcom_err.a(error_message.o): In function `et_list_lock': error_message.c:(.text+0x9d): undefined reference to `sem_wait' collect2: ld returned 1 exit status Waf: Leaving directory `/tmp/samba-4.0.0alpha14/source4/bin' Build failed: -> task failed (err #1): {task: cc_link asn1_rfc2459_asn1_65.o,der_get_60.o,der_put_60.o,der_free_60.o,der_format_60.o,der_length_60.o,der_copy_60.o,der_cmp_60.o,extra_60.o,t...

I'm not observing any noticeable performance differences, but I'm liking the diffstat. I can't push this patch until we release a new libnbd version with the _notify API addition, but am posting it now for playing with things. Eric Blake (2): nbd: Move transaction info from heap to stack nbd: Use nbdkit aio_*_notify variants plugins/nbd/nbd.c | 217

Attached is a patch and my service.c if there is any difficulty applying the patch. I did the following: 1. Created a ruby thread (Ruby_Service_Ctrl), that polls against a simple integer value (protected by a critical section). I was worried this would be "expensive"; however, I found the rb_thread_polling method and it seems to work well. 2. When an event occurs in Service_Ctrl it

.../* Perform the reply half of a transaction. */ static int -nbd_reply (struct handle *h, int fd) +nbd_reply (struct handle *h, struct transaction *trans) { int err; - if (read (fd, &err, sizeof err) != sizeof err) { - nbdkit_debug ("failed to read pipe: %m"); + while ((err = sem_wait (&trans->sem)) == -1 && errno == EINTR) + /* try again */; + if (err) { + nbdkit_debug ("failed to wait on semaphore: %m"); err = EIO; } - close (fd); + else + err = trans->err; + if (sem_destroy (&trans->sem)) + abort (); + free (trans);...

These three patches (for discussion only, NOT to be applied) implement a mutex system that lets the user limit the number of libguestfs instances that can be launched per host. There are two uses that I have identified for this: firstly so we can enable parallel-tests (the default in automake >= 1.13) without blowing up the host. Secondly oVirt has raised concerns about how to limit the

...8 0x0807b8ec in ?? () No symbol table info available. #9 0xb5b4bd9c in ?? () No symbol table info available. #10 0x00000000 in ?? () No symbol table info available. Thread 10 (Thread 0xb574fb90 (LWP 22835)): #0 0xffffe410 in __kernel_vsyscall () No symbol table info available. #1 0xb7f2f65e in sem_wait at GLIBC_2.0 () from /lib/i686/cmov/libpthread.so.0 No symbol table info available. #2 0x0630ba64 in check_pending_signals () from /usr/lib/jvm/java-6-sun-1.6.0.03/jre/lib/i386/client/libjvm.so No symbol table info available. #3 0x0630900d in os::signal_wait () from /usr/lib/jvm/java-6-su...

...;failed to post semaphore: %m"); - abort (); - } - } - return NULL; -} - -/* Perform the reply half of a transaction. */ -static int -nbd_reply (struct handle *h, struct transaction *trans) -{ - int err; - - if (!trans) { - assert (errno); - return -1; - } - - while ((err = sem_wait (&trans->sem)) == -1 && errno == EINTR) - /* try again */; - if (err) { - nbdkit_debug ("failed to wait on semaphore: %m"); - err = EIO; - } - else - err = trans->err; - if (sem_destroy (&trans->sem)) - abort (); - free (trans); - errno = err;...

Patch 1 played with an early draft of Rich's Fedora 30 libnbd package: https://bugzilla.redhat.com/show_bug.cgi?id=1713767#c17 Note that comment 21 provides a newer package 0.1.1-1 with a different API; and that libnbd has more unreleased API changes in the pipeline (whether that will be called 0.2 or 0.1.2); so we'll have to tweak things based on what is actually available in distros.

libnbd-0.1.2-1 is now available in Fedora 29/30 updates-testing, although it was not compiled against libxml2 so it lacks uri support (I ended up testing patch 4 with a self-built libnbd). Diffs since v1 - rebase to master, bump from libnbd 0.1 to 0.1.2, add URI support, better timing results Still not done - patch 5 needs associated tests Eric Blake (5): nbd: Check for libnbd nbd:

libnbd-0.1.4-1 is now available in Fedora 29/30 updates testing. Diffs since v2 - rebase to master, bump from libnbd 0.1.2 to 0.1.3+, add tests to TLS usage which flushed out the need to turn relative pathnames into absolute, doc tweaks Now that the testsuite covers TLS and libnbd has been fixed to provide the things I found lacking when developing v2, I'm leaning towards pushing this on