On Thu, Mar 25, 2010 at 05:27:16PM +0000, Daniel P. Berrange wrote:
> The QEMU cpu affinity is used in NUMA scenarios to ensure that
> guest memory is allocated from a specific node. Normally memory
> is allocate on demand in vCPU threads, but when using hugepages
> the initial thread leader allocates memory upfront. libvirt was
> not setting affinity of the thread leader, or I/O threads. This
> patch changes the code to set the process affinity in between
> the fork()/exec() of QEMU. This ensures that every single QEMU
> thread gets the affinity
>
> * src/qemu/qemu_driver.c: Set affinity on entire QEMU process
> at startup
> ---
> src/qemu/qemu_driver.c | 29 ++++++++++++++++-------------
> 1 files changed, 16 insertions(+), 13 deletions(-)
>
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 257f914..2598deb 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -1701,6 +1701,9 @@ qemuDetectVcpuPIDs(struct qemud_driver *driver,
> return 0;
> }
>
> +/*
> + * To be run between fork/exec of QEMU only
> + */
> static int
> qemudInitCpuAffinity(virDomainObjPtr vm)
> {
> @@ -1708,7 +1711,8 @@ qemudInitCpuAffinity(virDomainObjPtr vm)
> virNodeInfo nodeinfo;
> unsigned char *cpumap;
> int cpumaplen;
> - qemuDomainObjPrivatePtr priv = vm->privateData;
> +
> + DEBUG0("Setting CPU affinity");
>
> if (nodeGetInfo(NULL, &nodeinfo) < 0)
> return -1;
> @@ -1740,14 +1744,14 @@ qemudInitCpuAffinity(virDomainObjPtr vm)
> VIR_USE_CPU(cpumap, i);
> }
>
> - /* The XML config only gives a per-VM affinity, so we apply
> - * the same mapping to all vCPUs */
> - for (i = 0 ; i < priv->nvcpupids ; i++) {
> - if (virProcessInfoSetAffinity(priv->vcpupids[i],
> - cpumap, cpumaplen, maxcpu) < 0) {
> - VIR_FREE(cpumap);
> - return -1;
> - }
> + /* We are assuming we are running between fork/exec of QEMU, so
> + * that getpid() gives the QEMU process ID and we know that
> + * no threads are running.
> + */
> + if (virProcessInfoSetAffinity(getpid(),
> + cpumap, cpumaplen, maxcpu) < 0) {
> + VIR_FREE(cpumap);
> + return -1;
> }
> VIR_FREE(cpumap);
>
> @@ -2653,6 +2657,9 @@ struct qemudHookData {
> static int qemudSecurityHook(void *data) {
> struct qemudHookData *h = data;
>
> + if (qemudInitCpuAffinity(h->vm) < 0)
> + return -1;
> +
> if (qemuAddToCgroup(h->driver, h->vm->def) < 0)
> return -1;
>
> @@ -2943,10 +2950,6 @@ static int qemudStartVMDaemon(virConnectPtr conn,
> if (qemuDetectVcpuPIDs(driver, vm) < 0)
> goto abort;
>
> - DEBUG0("Setting CPU affinity");
> - if (qemudInitCpuAffinity(vm) < 0)
> - goto abort;
> -
> DEBUG0("Setting any required VM passwords");
> if (qemuInitPasswords(conn, driver, vm, qemuCmdFlags) < 0)
> goto abort;
ACK,
Daniel
--
Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/
daniel@xxxxxxxxxxxx | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library http://libvirt.org/
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