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

[Dr. David Alan Gilbert]

* zhanghailiang (address@hidden) 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 <address@hidden>
> Signed-off-by: zhanghailiang <address@hidden>
> Signed-off-by: Li Zhijian <address@hidden>
> Reviewed-by: Dr. David Alan Gilbert <address@hidden>
> ---
>  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.

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 / address@hidden / Manchester, UK