On Sun, Feb 22, 2015 at 1:36 PM, Hu Jun <jhu_com@xxxxxxx> wrote: > Hi guys: > > env: > [root@cloudf ~]# uname -a > Linux cloudf.fedora.com 3.18.7-100.fc20.x86_64 #1 SMP Wed Feb 11 19:01:50 > UTC 2015 x86_64 x86_64 x86_64 GNU/Linux > [root@cloudf ~]# rpm -q qemu-kvm > qemu-kvm-1.6.2-13.fc20.x86_64 > > I found there is a "futex" thead after creating a kvm guest by the > command:"/usr/bin/qemu-system-x86_64 -machine accel=kvm -hda > /opt/todaygoods_SLES_11_SP3_JeOS.x86_64-0.0.2.raw -vnc 192.168.0.110:6" > > root@cloudf task]# ps aux | grep qemu > root 13111 0.3 2.8 546760 227340 pts/3 S+ 18:26 0:12 gdb > qemu-system-x86_64 > root 14379 85.2 2.0 699004 165496 pts/3 tl 18:49 31:12 > /usr/bin/qemu-system-x86_64 -machine accel=kvm -hda > /opt/todaygoods_SLES_11_SP3_JeOS.x86_64-0.0.2.raw -vnc 192.168.0.110:6 > > the process 14379 has three threads, I'm familiar with the two of them > except the third thread (lwp :14418) > > [root@cloudf 14379]# cd /proc/14379/ > [root@cloudf 14379]# cat task/14 > 14379/ 14416/ 14418/ > [root@cloudf 14379]# cat task/14379/stack > [<ffffffff8121d1e9>] poll_schedule_timeout+0x49/0x70 > [<ffffffff8121e8e4>] do_sys_poll+0x484/0x5c0 > [<ffffffff8121eb24>] SyS_poll+0x74/0x110 > [<ffffffff8174cfa9>] system_call_fastpath+0x12/0x17 > [<ffffffffffffffff>] 0xffffffffffffffff > [root@cloudf 14379]# cat task/14416/stack > [<ffffffffa05cf92d>] kvm_arch_vcpu_ioctl_run+0xb0d/0x1280 [kvm] > [<ffffffffa05b7bb2>] kvm_vcpu_ioctl+0x292/0x5c0 [kvm] > [<ffffffff8121c710>] do_vfs_ioctl+0x2e0/0x4a0 > [<ffffffff8121c951>] SyS_ioctl+0x81/0xa0 > [<ffffffff8174cfa9>] system_call_fastpath+0x12/0x17 > [<ffffffffffffffff>] 0xffffffffffffffff > [root@cloudf 14379]# cat task/14418/stack > [<ffffffff8110b6e0>] futex_wait_queue_me+0xd0/0x130 > [<ffffffff8110b9e6>] futex_wait+0x176/0x270 > [<ffffffff8110dc7e>] do_futex+0x10e/0xac0 > [<ffffffff8110e6b0>] SyS_futex+0x80/0x180 > [<ffffffff8174cfa9>] system_call_fastpath+0x12/0x17 > [<ffffffffffffffff>] 0xffffffffffffffff > > what's the "futex" thread doing when create a kvm guest ? I deeped into > the qemu code , but I failed to find where call "futex" system call. It is unlikely that you will find any call to "futex" in the source code of an application. It doesn't even have glibc interface. Most of the time it is an implementation detail for something else. For instance pthread_join is implemented using the futex system call. But the question here is ... what is the problem that you are trying to solve? _______________________________________________ kernel mailing list kernel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/kernel
