On Thu, May 30, 2013 at 05:57:21PM +0800, Wanlong Gao wrote: > > Use mbind to pin guest numa node memory to host nodes manually. > > > > If we are not able to pin memory to host node, we may meet the > > cross node memory access performance regression. > > > > With this patch, we can add manual pinning host node like this: > > -m 1024 -numa node,cpus=0,nodeid=0,mem=512,pin=0 -numa > > node,nodeid=1,cpus=1,mem=512,pin=1 > > > > And, if PCI-passthrough is used, direct-attached-device uses DMA transfer > > between device and qemu process. All pages of the guest will be pinned by > > get_user_pages(). > > > > KVM_ASSIGN_PCI_DEVICE ioctl > > kvm_vm_ioctl_assign_device() > > =>kvm_assign_device() > > => kvm_iommu_map_memslots() > > => kvm_iommu_map_pages() > > => kvm_pin_pages() > > > > So, with direct-attached-device, all guest page's page count will be +1 and > > any page migration will not work. AutoNUMA won't too. And direction by > > libvirt is *ignored*. > > > > Above all, we need manual pinning memory to host node to avoid > > such cross nodes memmory access performance regression.
I believe a similar approach (letting QEMU do the pinning itself) was already proposed and rejected. See: http://article.gmane.org/gmane.comp.emulators.kvm.devel/58835 http://article.gmane.org/gmane.comp.emulators.kvm.devel/57684 An alternative approach was proposed at; http://article.gmane.org/gmane.comp.emulators.qemu/123001 (exporting virtual address information directly) and another one at: http://article.gmane.org/gmane.comp.emulators.qemu/157741 (keeping the files inside -mem-path-dir so they could be pinned manually by other programs) The approach I was planning to implement was the one proposed at: http://article.gmane.org/gmane.comp.emulators.kvm.devel/93476 (exporting memory backing information through QMP, instead of depending on predictable filenames on -mem-path-dir) > > > > Signed-off-by: Wanlong Gao <gaowanl...@cn.fujitsu.com> > > --- > > exec.c | 21 +++++++++++++++++++++ > > include/sysemu/sysemu.h | 1 + > > vl.c | 13 +++++++++++++ > > 3 files changed, 35 insertions(+) > > > > diff --git a/exec.c b/exec.c > > index aec65c5..fe929ef 100644 > > --- a/exec.c > > +++ b/exec.c > > @@ -36,6 +36,8 @@ > > #include "qemu/config-file.h" > > #include "exec/memory.h" > > #include "sysemu/dma.h" > > +#include "sysemu/sysemu.h" > > +#include "qemu/bitops.h" > > #include "exec/address-spaces.h" > > #if defined(CONFIG_USER_ONLY) > > #include <qemu.h> > > @@ -1081,6 +1083,25 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, > > void *host, > > memory_try_enable_merging(new_block->host, size); > > } > > } > > + > > + if (nb_numa_nodes > 0 && !strcmp(mr->name, "pc.ram")) { > > + int i; > > + uint64_t nodes_mem = 0; > > + unsigned long *maskp = g_malloc0(sizeof(*maskp)); > > + for (i = 0; i < nb_numa_nodes; i++) { > > + *maskp = 0; > > + if (node_pin[i] != -1) { > > + set_bit(node_pin[i], maskp); > > + if (qemu_mbind(new_block->host + nodes_mem, node_mem[i], > > + QEMU_MPOL_BIND, maskp, MAX_NODES, 0)) { > > + perror("qemu_mbind"); > > + exit(1); > > + } > > + } > > + nodes_mem += node_mem[i]; > > + } > > + } > > + > > new_block->length = size; > > > > /* Keep the list sorted from biggest to smallest block. */ > > diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h > > index 2fb71af..ebf6580 100644 > > --- a/include/sysemu/sysemu.h > > +++ b/include/sysemu/sysemu.h > > @@ -131,6 +131,7 @@ extern QEMUClock *rtc_clock; > > #define MAX_CPUMASK_BITS 255 > > extern int nb_numa_nodes; > > extern uint64_t node_mem[MAX_NODES]; > > +extern int node_pin[MAX_NODES]; > > extern unsigned long *node_cpumask[MAX_NODES]; > > > > #define MAX_OPTION_ROMS 16 > > diff --git a/vl.c b/vl.c > > index 5555b1d..3768002 100644 > > --- a/vl.c > > +++ b/vl.c > > @@ -253,6 +253,7 @@ static QTAILQ_HEAD(, FWBootEntry) fw_boot_order = > > > > int nb_numa_nodes; > > uint64_t node_mem[MAX_NODES]; > > +int node_pin[MAX_NODES]; > > unsigned long *node_cpumask[MAX_NODES]; > > > > uint8_t qemu_uuid[16]; > > @@ -1390,6 +1391,17 @@ static void numa_add(const char *optarg) > > } > > node_mem[nodenr] = sval; > > } > > + > > + if (get_param_value(option, 128, "pin", optarg) != 0) { > > + int unsigned long long pin_node; > > + if (parse_uint_full(option, &pin_node, 10) < 0) { > > + fprintf(stderr, "qemu: Invalid pinning nodeid: %s\n", > > optarg); > > + exit(1); > > + } else { > > + node_pin[nodenr] = pin_node; > > + } > > + } > > + > > if (get_param_value(option, 128, "cpus", optarg) != 0) { > > numa_node_parse_cpus(nodenr, option); > > } > > @@ -2921,6 +2933,7 @@ int main(int argc, char **argv, char **envp) > > > > for (i = 0; i < MAX_NODES; i++) { > > node_mem[i] = 0; > > + node_pin[i] = -1; > > node_cpumask[i] = bitmap_new(MAX_CPUMASK_BITS); > > } > > > > > > > -- Eduardo