Re: [Qemu-devel] [PATCH 12/15] savevm: split the process of different stages for loadvm/savevm

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Hailiang Zhang (zhang.zhanghailiang@huawei.com) wrote:
> On 2017/4/8 1:18, Dr. David Alan Gilbert wrote:
> > * zhanghailiang (zhang.zhanghailiang@huawei.com) wrote:
> > > There are several stages during loadvm/savevm process. In different stage,
> > > migration incoming processes different types of sections.
> > > We want to control these stages more accuracy, it will benefit COLO
> > > performance, we don't have to save type of QEMU_VM_SECTION_START
> > > sections everytime while do checkpoint, besides, we want to separate
> > > the process of saving/loading memory and devices state.
> > > 
> > > So we add three new helper functions: qemu_loadvm_state_begin(),
> > > qemu_load_device_state() and qemu_savevm_live_state() to achieve
> > > different process during migration.
> > > 
> > > Besides, we make qemu_loadvm_state_main() and qemu_save_device_state()
> > > public.
> > > 
> > > Cc: Juan Quintela <quintela@redhat.com>
> > > Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> > > Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
> > > Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > > ---
> > >   include/sysemu/sysemu.h |  6 ++++++
> > >   migration/savevm.c      | 55 ++++++++++++++++++++++++++++++++++++++++++-------
> > >   2 files changed, 54 insertions(+), 7 deletions(-)
> > > 
> > > diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> > > index 7ed665a..95cae41 100644
> > > --- a/include/sysemu/sysemu.h
> > > +++ b/include/sysemu/sysemu.h
> > > @@ -132,7 +132,13 @@ void qemu_savevm_send_postcopy_ram_discard(QEMUFile *f, const char *name,
> > >                                              uint64_t *start_list,
> > >                                              uint64_t *length_list);
> > > +void qemu_savevm_live_state(QEMUFile *f);
> > > +int qemu_save_device_state(QEMUFile *f);
> > > +
> > >   int qemu_loadvm_state(QEMUFile *f);
> > > +int qemu_loadvm_state_begin(QEMUFile *f);
> > > +int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis);
> > > +int qemu_load_device_state(QEMUFile *f);
> > >   extern int autostart;
> > > diff --git a/migration/savevm.c b/migration/savevm.c
> > > index 9c2d239..dac478b 100644
> > > --- a/migration/savevm.c
> > > +++ b/migration/savevm.c
> > > @@ -54,6 +54,7 @@
> > >   #include "qemu/cutils.h"
> > >   #include "io/channel-buffer.h"
> > >   #include "io/channel-file.h"
> > > +#include "migration/colo.h"
> > >   #ifndef ETH_P_RARP
> > >   #define ETH_P_RARP 0x8035
> > > @@ -1279,13 +1280,21 @@ done:
> > >       return ret;
> > >   }
> > > -static int qemu_save_device_state(QEMUFile *f)
> > > +void qemu_savevm_live_state(QEMUFile *f)
> > >   {
> > > -    SaveStateEntry *se;
> > > +    /* save QEMU_VM_SECTION_END section */
> > > +    qemu_savevm_state_complete_precopy(f, true);
> > > +    qemu_put_byte(f, QEMU_VM_EOF);
> > > +}
> > > -    qemu_put_be32(f, QEMU_VM_FILE_MAGIC);
> > > -    qemu_put_be32(f, QEMU_VM_FILE_VERSION);
> > > +int qemu_save_device_state(QEMUFile *f)
> > > +{
> > > +    SaveStateEntry *se;
> > > +    if (!migration_in_colo_state()) {
> > > +        qemu_put_be32(f, QEMU_VM_FILE_MAGIC);
> > > +        qemu_put_be32(f, QEMU_VM_FILE_VERSION);
> > > +    }
> > Note that got split out into qemu_savevm_state_header() at some point.
> 
> Do you mean i should use the wrapper qemu_savevm_state_heade() here ?

Yes, I think so; best to keep the code that writes the file headers in one place.

Dave

> > Dave
> > 
> > >       cpu_synchronize_all_states();
> > >       QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> > > @@ -1336,8 +1345,6 @@ enum LoadVMExitCodes {
> > >       LOADVM_QUIT     =  1,
> > >   };
> > > -static int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis);
> > > -
> > >   /* ------ incoming postcopy messages ------ */
> > >   /* 'advise' arrives before any transfers just to tell us that a postcopy
> > >    * *might* happen - it might be skipped if precopy transferred everything
> > > @@ -1942,7 +1949,7 @@ qemu_loadvm_section_part_end(QEMUFile *f, MigrationIncomingState *mis)
> > >       return 0;
> > >   }
> > > -static int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis)
> > > +int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis)
> > >   {
> > >       uint8_t section_type;
> > >       int ret = 0;
> > > @@ -2080,6 +2087,40 @@ int qemu_loadvm_state(QEMUFile *f)
> > >       return ret;
> > >   }
> > > +int qemu_loadvm_state_begin(QEMUFile *f)
> > > +{
> > > +    MigrationIncomingState *mis = migration_incoming_get_current();
> > > +    Error *local_err = NULL;
> > > +    int ret;
> > > +
> > > +    if (qemu_savevm_state_blocked(&local_err)) {
> > > +        error_report_err(local_err);
> > > +        return -EINVAL;
> > > +    }
> > > +    /* Load QEMU_VM_SECTION_START section */
> > > +    ret = qemu_loadvm_state_main(f, mis);
> > > +    if (ret < 0) {
> > > +        error_report("Failed to loadvm begin work: %d", ret);
> > > +    }
> > > +    return ret;
> > > +}
> > > +
> > > +int qemu_load_device_state(QEMUFile *f)
> > > +{
> > > +    MigrationIncomingState *mis = migration_incoming_get_current();
> > > +    int ret;
> > > +
> > > +    /* Load QEMU_VM_SECTION_FULL section */
> > > +    ret = qemu_loadvm_state_main(f, mis);
> > > +    if (ret < 0) {
> > > +        error_report("Failed to load device state: %d", ret);
> > > +        return ret;
> > > +    }
> > > +
> > > +    cpu_synchronize_all_post_init();
> > > +    return 0;
> > > +}
> > > +
> > >   int save_vmstate(Monitor *mon, const char *name)
> > >   {
> > >       BlockDriverState *bs, *bs1;
> > > -- 
> > > 1.8.3.1
> > > 
> > > 
> > --
> > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> > 
> > .
> > 
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK