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2011-07-23Register Linux dyntick timer as per-thread signalJan Kiszka1-0/+11
Derived from kvm-tool patch http://thread.gmane.org/gmane.comp.emulators.kvm.devel/74309 Ingo Molnar pointed out that sending the timer signal to the whole process, just blocking it everywhere, is suboptimal with an increasing number of threads. QEMU is also using this pattern so far. Linux provides a (non-portable) way to restrict the signal to a single thread: We can use SIGEV_THREAD_ID unless we are forced to emulate signalfd via an additional thread. That case could theoretically be optimized as well, but it doesn't look worth bothering. Reviewed-by: Richard Henderson <rth@twiddle.net> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2011-06-10sigfd: use pthread_sigmaskAlexander Graf1-1/+1
Qemu uses signalfd to figure out, if a signal occured without the need to actually receive the signal. Instead, it can read from the fd to receive its news. Now, we obviously don't always have signalfd around. Especially not on non-Linux systems. So what we do there is that we create a new thread, block that thread on all signals and simply call sigwait to wait for a signal we're interested in to occur. This all sounds great, but what we're really doing is: sigset_t all; sigfillset(&all); sigprocmask(SIG_BLOCK, &all, NULL); which - on Darwin - blocks all signals on the current _process_, not only on the current thread. To block signals on the thread, we can use pthread_sigmask(). This patch does that, assuming that my above analysis is correct, and thus renders Qemu useable on Darwin again. Reported-by: Andreas Färber <andreas.faerber@web.de> Acked-by: Paolo Bonizni <pbonzini@redhat.com> CC: Jan Kiszka <jan.kiszka@siemens.com> CC: Anthony Liguori <anthony@codemonkey.ws> Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
2011-02-25Use sigwait instead of sigwaitinfo.Tristan Gingold1-18/+18
Fix compilation failure on Darwin. Signed-off-by: Tristan Gingold <gingold@adacore.com> Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2010-10-20signalfd compatibilityMarcelo Tosatti1-0/+117
Port qemu-kvm's signalfd compat code. commit 5a7fdd0abd7cd24dac205317a4195446ab8748b5 Author: Anthony Liguori <aliguori@us.ibm.com> Date: Wed May 7 11:55:47 2008 -0500 Use signalfd() in io-thread This patch reworks the IO thread to use signalfd() instead of sigtimedwait() This will eliminate the need to use SIGIO everywhere. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2008-10-08Fix IO performance regression in sparcaliguori1-127/+0
Replace signalfd with signal handler/pipe. There is no way to interrupt the CPU execution loop when a file descriptor becomes readable. This results in a large performance regression in sparc emulation during bootup. This patch switches us to signal handler/pipe which was originally suggested by Ian Jackson. The signal handler lets us interrupt the CPU emulation loop while the write to a pipe lets us avoid the select/signal race condition. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5451 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-27Make compatfd fallback more robustaliguori1-5/+4
Be more friendly when signalfd() fails, and also add configure checks to detect that syscall(SYS_signalfd) actually works. malc pointed out that some installs do not have /usr/include/linux headers that are in sync with the glibc headers so why SYS_signalfd is defined, it's #defined to _NR_signalfd which is not defined in the /usr/include/linux header. While this is a distro bug, it doesn't hurt to do a more thorough job in detection. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5334 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-27Fix whitespace damage in compatfdaliguori1-28/+28
Spotted by malc. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5333 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-10Add missing files from previous commit.aliguori1-0/+128
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5188 c046a42c-6fe2-441c-8c8c-71466251a162