[dpdk-dev] [DPDK-memory] how qemu waste such long time under dpdk huge page envriment?

[Sam]

Hi,

I print all system call by `strace -f -T -tt -e trace=all -o output.txt
$QEMU_CMD`, and I found this:

5900  11:08:11.288701 nanosleep({0, 10000000}, 0x7ff103c13a80) = 0
> <0.010171>
> 5900  11:08:11.299052 futex(0x7ff10be24340, FUTEX_WAIT_PRIVATE, 2, NULL
> <unfinished ...>
> 5899  11:08:20.138492 rt_sigaction(SIGBUS, {0x7ff10b5b1040, [],
> SA_RESTORER|SA_SIGINFO, 0x7ff1085fd100}, NULL, 8) = 0 <0.000012>
> 5899  11:08:20.138598 rt_sigprocmask(SIG_SETMASK, [BUS USR1 ALRM IO],
> NULL, 8) = 0 <0.000008>
> 5899  11:08:20.138646 mmap(NULL, 266240, PROT_READ|PROT_WRITE,
> MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7ff10b380000 <0.000013>
> 5899  11:08:20.138793 mmap(NULL, 266240, PROT_READ|PROT_WRITE,
> MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7ff10b33f000 <0.000009>


I don't know who call `futex`, and why waste such long time. And for `mmap`
system call, I don't found this system call waste too much time.

WHY....


2017-06-16 16:59 GMT+08:00 Bruce Richardson <bruce.richardson at intel.com>:

> On Fri, Jun 16, 2017 at 04:26:40PM +0800, Sam wrote:
> > BTW, while running ovs-dpdk, this log is also take long time, does that
> > mean dpdk request large memory take long time?
> >
> > EAL: Setting up physically contiguous memory...
> >
>
> When running with 1G pages, I found that the mmap system call takes a
> considerable amount of time to execute. I think this is due to the
> kernel zero-ing out the 1G pages. IIRC on one system I measured it as
> taking
> about 0.4 seconds per 1G page.
>
> /Bruce
>
> >
> > 2017-06-16 16:11 GMT+08:00 Sam <batmanustc at gmail.com>:
> >
> > > Hi all,
> > >
> > > I'm running `QEMU_CMD ...` to create a vm under dpdk huge page
> envriment
> > > (which set huge page 1G). And I enable all events in qemu.
> > >
> > > For qemu and ovs-dpdk(ovs-2.4.9 with dpdk-2.2.0) environment, detail
> log
> > > is:
> > >
> > > > 30012 at 1497443246.678304:object_dynamic_cast_assert
> > > qemu:memory-region->qemu:memory-region (/home/hu
> > > > anghuai/cloud/contrib/qemu-2.6.0/memory.c:1076:memory_region_initfn)
> > > > 30012 at 1497443256.274866:object_dynamic_cast_assert
> > > qio-channel-socket->qio-channel-socket (io/chann
> > > > el-socket.c:389:qio_channel_socket_init)
> > >
> > >
> > > I don't know why qemu doing 'memory_region_initfn' function in this 10
> > > second, does anyone know this?
> > >
> > > static void memory_region_initfn(Object *obj)
> > >> {
> > >>     MemoryRegion *mr = MEMORY_REGION(obj);
> > >>     ObjectProperty *op;
> > >>     mr->ops = &unassigned_mem_ops;
> > >>     mr->enabled = true;
> > >>     mr->romd_mode = true;
> > >>     mr->global_locking = true;
> > >>     mr->destructor = memory_region_destructor_none;
> > >>     QTAILQ_INIT(&mr->subregions);
> > >>     QTAILQ_INIT(&mr->coalesced);
> > >>     op = object_property_add(OBJECT(mr), "container",
> > >>                              "link<" TYPE_MEMORY_REGION ">",
> > >>                              memory_region_get_container,
> > >>                              NULL, /* memory_region_set_container */
> > >>                              NULL, NULL, &error_abort);
> > >>     op->resolve = memory_region_resolve_container;
> > >>     object_property_add(OBJECT(mr), "addr", "uint64",
> > >>                         memory_region_get_addr,
> > >>                         NULL, /* memory_region_set_addr */
> > >>                         NULL, NULL, &error_abort);
> > >>     object_property_add(OBJECT(mr), "priority", "uint32",
> > >>                         memory_region_get_priority,
> > >>                         NULL, /* memory_region_set_priority */
> > >>                         NULL, NULL, &error_abort);
> > >>     object_property_add_bool(OBJECT(mr), "may-overlap",
> > >>                              memory_region_get_may_overlap,
> > >>                              NULL, /* memory_region_set_may_overlap */
> > >>                              &error_abort);
> > >>     object_property_add(OBJECT(mr), "size", "uint64",
> > >>                         memory_region_get_size,
> > >>                         NULL, /* memory_region_set_size, */
> > >>                         NULL, NULL, &error_abort);
> > >> }
> > >
> > >
> > > Thank you~
> > >
>