On Thu, Jun 23, 2016 at 01:25:29PM +0100, Jaroslav Safka wrote:
> Add conversion from xml to argv for subelements
> source,access and allocation of <memoryBacking>
>
> This change introduces support for preallocated
> shared file descriptor based memory backing.
> It allows vhost-user to be used without hugepages.
>
> Configured by these elements:
> <memoryBacking>
> <source type="file|anonymous"/>
> <access Mode="shared|private"/>
> <allocation mode="immediate|ondemand"/>
> </memoryBacking>
> ---
> src/qemu/qemu_command.c | 56 ++++++++++++++++++++++
> src/qemu/qemu_command.h | 4 ++
> .../qemuxml2argv-memorybacking-set.args | 6 ++-
> tests/qemuxml2argvtest.c | 3 ++
> 4 files changed, 68 insertions(+), 1 deletion(-)
>
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index 6944129..321e71f 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -9328,6 +9328,9 @@ qemuBuildCommandLine(virQEMUDriverPtr driver,
> if (qemuBuildNVRAMCommandLine(cmd, def, qemuCaps) < 0)
> goto error;
>
> + if (qemuBuildMemoryBackendCommandLine(cmd, def, qemuCaps) < 0)
> + goto error;
> +
> if (snapshot)
> virCommandAddArgList(cmd, "-loadvm", snapshot->def->name, NULL);
>
> @@ -9592,3 +9595,56 @@ qemuBuildChrDeviceStr(char **deviceStr,
>
> return ret;
> }
> +
> +static char *
> +qemuBuildMemoryBackendFileStr(const virDomainDef *def)
> +{
> + virBuffer buf = VIR_BUFFER_INITIALIZER;
> + const char template[] = "memory-backend-file,id=mem,size=1024M,mem-path=/var/lib/libvirt/qemu";
As Michael has pointed out - this is just insanity - you can't
hardcode memory size like this.
> +
> + if (VIR_DOMAIN_MEMORY_ACCESS_SHARED == def->mem.access) {
> + // add ",share=on" to -object memory-backend-file
> + virBufferAsprintf(&buf, "%s,share=on", template);
> + } else {
> + virBufferAsprintf(&buf, "%s", template);
> + }
> +
> +
> + if (virBufferCheckError(&buf) < 0)
> + goto error;
> +
> + return virBufferContentAndReset(&buf);
> +
> + error:
> + virBufferFreeAndReset(&buf);
> + return NULL;
> +}
> +
> +
> +int
> +qemuBuildMemoryBackendCommandLine(virCommandPtr cmd,
> + const virDomainDef *def,
> + virQEMUCapsPtr qemuCaps __attribute__((unused)))
> +{
> + char *optstr = NULL;
> +
> + if (VIR_DOMAIN_MEMORY_ALLOCATION_IMMEDIATE == def->mem.allocation) {
> + // add '-mem-prealloc'
> + virCommandAddArg(cmd, "-mem-prealloc");
> + }
> +
You need todo
> + if (VIR_DOMAIN_MEMORY_SOURCE_FILE == def->mem.source) {
> + optstr = qemuBuildMemoryBackendFileStr(def);
> + if (optstr) {
> + virCommandAddArg(cmd, "-object");
> + virCommandAddArg(cmd, optstr);
> + VIR_FREE(optstr);
> + }
You're ignoring the error here - you must propagate the
NULL error.
> +
> + // add '-object memory-backend-file,id=mem,size=1024M,mem-path=/var/lib/libvirt/qemu'
> + // add '-numa node,memdev=mem'
> + virCommandAddArgList(cmd, "-numa", "node,memdev=mem", NULL);
> + }
We already have code that runs when the guest has NUMA topology
configured. This existing code must be adapted to honour the
top level VIR_DOMAIN_MEMORY_ACCESS_* setting, vs the per-cell
setting. This new code you're adding should only be used when
a non-NUMA guest config is requested, and it should be using
the -mem-path command line argument to set the file - not =
creating a NUMA topology in a non-NUMA requested guest.
Regards,
Daniel
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