Re: [Qemu-devel] [RFC PATCH v0] spapr: Disable CPU unplug in TCG mode
On Wed, Sep 21, 2016 at 03:31:00PM +1000, David Gibson wrote:
> On Wed, Sep 21, 2016 at 10:18:00AM +0530, Bharata B Rao wrote:
> > CPU unplug doesn't work in TCG mode currently and causes frequent system
> > freeze. In addition to other potential problems, the main problem arises
> > of out the requirement to support synchronous removal of a CPU thread.
> > The CPU thread that performs the cleanup of the unplugged CPU, kicks and
> > waits for the unplugged CPU thread to finish. This wait never finishes in
> > TCG mode when the waiting thread and the unplugged CPU thread are one and
> > the same.
> >
> > So wait till proper MTTCG support is available before enabling
> > CPU unplug in TCG mode.
>
> MTTCG seems like a very big hammer to fix this with. Surely we could
> come up with a simpler interlock that would work for TCG in the
> meantime.
The following hack fixes the issue mostly. I still see some occasional
hangs which points to other potential problems.
diff --git a/cpus.c b/cpus.c
index 8ad1eb4..7dc7d09 100644
--- a/cpus.c
+++ b/cpus.c
@@ -1526,8 +1526,13 @@ void cpu_remove(CPUState *cpu)
void cpu_remove_sync(CPUState *cpu)
{
cpu_remove(cpu);
-while (cpu->created) {
-qemu_cond_wait(&qemu_cpu_cond, &qemu_global_mutex);
+if (!kvm_enabled()) {
+qemu_tcg_destroy_vcpu(cpu);
+cpu->created = false;
+} else {
+while (cpu->created) {
+qemu_cond_wait(&qemu_cpu_cond, &qemu_global_mutex);
+}
}
}
@@ -1573,6 +1578,9 @@ static void qemu_tcg_init_vcpu(CPUState *cpu)
/* For non-MTTCG cases we share the thread */
cpu->thread = single_tcg_cpu_thread;
cpu->halt_cond = single_tcg_halt_cond;
+cpu->thread_id = first_cpu->thread_id;
+cpu->created = true;
+cpu->can_do_io = 1;
}
}
diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index dc058e5..9558fc9 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -244,6 +244,7 @@ static void rtas_stop_self(PowerPCCPU *cpu,
sPAPRMachineState *spapr,
CPUPPCState *env = &cpu->env;
cs->halted = 1;
+cs->stop = true;
qemu_cpu_kick(cs);
/*
* While stopping a CPU, the guest calls H_CPPR which
This is however on Alex's MTTCG tree, I need to figure out which are
the fixes that are relavent from Alex's tree to get CPU unplug working
in TCG mode.
Regards,
Bharata.
Re: [Qemu-devel] [RFC PATCH v0] spapr: Disable CPU unplug in TCG mode
On Wed, Sep 21, 2016 at 10:18:00AM +0530, Bharata B Rao wrote:
> CPU unplug doesn't work in TCG mode currently and causes frequent system
> freeze. In addition to other potential problems, the main problem arises
> of out the requirement to support synchronous removal of a CPU thread.
> The CPU thread that performs the cleanup of the unplugged CPU, kicks and
> waits for the unplugged CPU thread to finish. This wait never finishes in
> TCG mode when the waiting thread and the unplugged CPU thread are one and
> the same.
>
> So wait till proper MTTCG support is available before enabling
> CPU unplug in TCG mode.
MTTCG seems like a very big hammer to fix this with. Surely we could
come up with a simpler interlock that would work for TCG in the
meantime.
>
> Signed-off-by: Bharata B Rao
> ---
> hw/ppc/spapr.c | 4
> 1 file changed, 4 insertions(+)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index ca77bb0..d7864c6 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2300,6 +2300,10 @@ static void spapr_machine_device_unplug(HotplugHandler
> *hotplug_dev,
> error_setg(errp, "CPU hot unplug not supported on this machine");
> return;
> }
> +if (!kvm_enabled()) {
> +error_setg(errp, "CPU hot unplug not supported in TCG mode");
> +return;
> +}
> spapr_core_unplug(hotplug_dev, dev, errp);
> }
> }
--
David Gibson| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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Re: [Qemu-devel] [RFC PATCH v0] spapr: Disable CPU unplug in TCG mode
On Tue, 09/20 22:02, no-re...@ec2-52-6-146-230.compute-1.amazonaws.com wrote: > BUILD fedora > ARCHIVE qemu.tgz > ARCHIVE dtc.tgz > COPY RUNNER > RUN test-mingw in fedora > tests/docker/Makefile.include:107: recipe for target > 'docker-run-test-mingw@fedora' failed > make: *** [docker-run-test-mingw@fedora] Error 137 Sorry for the false alarm, I think this is a test server problem. Fam
Re: [Qemu-devel] [RFC PATCH v0] spapr: Disable CPU unplug in TCG mode
Hi, Your series failed automatic build test. Please find the testing commands and their output below. If you have docker installed, you can probably reproduce it locally. Type: series Message-id: 1474433280-25652-1-git-send-email-bhar...@linux.vnet.ibm.com Subject: [Qemu-devel] [RFC PATCH v0] spapr: Disable CPU unplug in TCG mode === TEST SCRIPT BEGIN === #!/bin/bash set -e git submodule update --init dtc make J=8 docker-test-quick@centos6 make J=8 docker-test-mingw@fedora === TEST SCRIPT END === Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384 Switched to a new branch 'test' 4bcbc83 spapr: Disable CPU unplug in TCG mode === OUTPUT BEGIN === Submodule 'dtc' (git://git.qemu-project.org/dtc.git) registered for path 'dtc' Cloning into 'dtc'... Submodule path 'dtc': checked out '65cc4d2748a2c2e6f27f1cf39e07a5dbabd80ebf' BUILD centos6 ARCHIVE qemu.tgz ARCHIVE dtc.tgz COPY RUNNER RUN test-quick in centos6 No C++ compiler available; disabling C++ specific optional code Install prefix/tmp/qemu-test/src/tests/docker/install BIOS directory/tmp/qemu-test/src/tests/docker/install/share/qemu binary directory /tmp/qemu-test/src/tests/docker/install/bin library directory /tmp/qemu-test/src/tests/docker/install/lib module directory /tmp/qemu-test/src/tests/docker/install/lib/qemu libexec directory /tmp/qemu-test/src/tests/docker/install/libexec include directory /tmp/qemu-test/src/tests/docker/install/include config directory /tmp/qemu-test/src/tests/docker/install/etc local state directory /tmp/qemu-test/src/tests/docker/install/var Manual directory /tmp/qemu-test/src/tests/docker/install/share/man ELF interp prefix /usr/gnemul/qemu-%M Source path /tmp/qemu-test/src C compilercc Host C compiler cc C++ compiler Objective-C compiler cc ARFLAGS rv CFLAGS-O2 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -pthread -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -g QEMU_CFLAGS -I/usr/include/pixman-1-fPIE -DPIE -m64 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wall -Wundef -Wwrite-strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv -Wendif-labels -Wmissing-include-dirs -Wempty-body -Wnested-externs -Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers -Wold-style-declaration -Wold-style-definition -Wtype-limits -fstack-protector-all LDFLAGS -Wl,--warn-common -Wl,-z,relro -Wl,-z,now -pie -m64 -g make make install install pythonpython -B smbd /usr/sbin/smbd module supportno host CPU x86_64 host big endian no target list x86_64-softmmu aarch64-softmmu tcg debug enabled no gprof enabled no sparse enabledno strip binariesyes profiler no static build no pixmansystem SDL support yes (1.2.14) GTK support no GTK GL supportno VTE support no TLS priority NORMAL GNUTLS supportno GNUTLS rndno libgcrypt no libgcrypt kdf no nettleno nettle kdfno libtasn1 no curses supportno virgl support no curl support no mingw32 support no Audio drivers oss Block whitelist (rw) Block whitelist (ro) VirtFS supportno VNC support yes VNC SASL support no VNC JPEG support no VNC PNG support no xen support no brlapi supportno bluez supportno Documentation no PIE yes vde support no netmap supportno Linux AIO support no ATTR/XATTR support yes Install blobs yes KVM support yes RDMA support no TCG interpreter no fdt support yes preadv supportyes fdatasync yes madvise yes posix_madvise yes uuid support no libcap-ng support no vhost-net support yes vhost-scsi support yes vhost-vsock support yes Trace backendslog spice support no rbd support no xfsctl supportno smartcard support no libusbno usb net redir no OpenGL supportno OpenGL dmabufsno libiscsi support no libnfs supportno build guest agent yes QGA VSS support no QGA w32 disk info no QGA MSI support no seccomp support no coroutine backend ucontext coroutine poolyes GlusterFS support no Archipelago support no gcov gcov gcov enabled no TPM support yes libssh2 support no TPM passthrough yes QOM debugging yes vhdx no lzo support no snappy supportno bzip2 support no NUMA host support no tcmalloc support no jemalloc support no avx2 optimization no replication support yes GEN x86_64-softmmu/config-devices.mak.tmp GEN aarch64-softmmu/config-devices.mak.tmp GEN config-host.h GEN qemu-options.def GEN qmp-commands.h GEN qapi-types.h GEN qapi-visit.h GEN qapi-event.h GEN x86_64-softmmu/config-devices.mak GEN aarch
[Qemu-devel] [RFC PATCH v0] spapr: Disable CPU unplug in TCG mode
CPU unplug doesn't work in TCG mode currently and causes frequent system
freeze. In addition to other potential problems, the main problem arises
of out the requirement to support synchronous removal of a CPU thread.
The CPU thread that performs the cleanup of the unplugged CPU, kicks and
waits for the unplugged CPU thread to finish. This wait never finishes in
TCG mode when the waiting thread and the unplugged CPU thread are one and
the same.
So wait till proper MTTCG support is available before enabling
CPU unplug in TCG mode.
Signed-off-by: Bharata B Rao
---
hw/ppc/spapr.c | 4
1 file changed, 4 insertions(+)
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index ca77bb0..d7864c6 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2300,6 +2300,10 @@ static void spapr_machine_device_unplug(HotplugHandler
*hotplug_dev,
error_setg(errp, "CPU hot unplug not supported on this machine");
return;
}
+if (!kvm_enabled()) {
+error_setg(errp, "CPU hot unplug not supported in TCG mode");
+return;
+}
spapr_core_unplug(hotplug_dev, dev, errp);
}
}
--
2.7.4
