Re: [PATCH v2 07/10] migration: Make no compression operations into its own structure

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

* Juan Quintela (quintela@redhat.com) wrote:
> It will be used later.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> 
> ---
> Move setup of ->ops helper to proper place (wei)
> Rename s/none/nocomp/ (dave)
> Introduce MULTIFD_FLAG_NOCOMP
> ---
>  migration/migration.c |   9 ++
>  migration/migration.h |   1 +
>  migration/ram.c       | 194 ++++++++++++++++++++++++++++++++++++++++--
>  3 files changed, 196 insertions(+), 8 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index 93c6ed10a6..56203eb536 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -2213,6 +2213,15 @@ int migrate_multifd_channels(void)
>      return s->parameters.multifd_channels;
>  }
>  
> +int migrate_multifd_method(void)
> +{
> +    MigrationState *s;
> +
> +    s = migrate_get_current();
> +
> +    return s->parameters.multifd_compress;
> +}
> +
>  int migrate_use_xbzrle(void)
>  {
>      MigrationState *s;
> diff --git a/migration/migration.h b/migration/migration.h
> index 545f283ae7..d3ea45e25a 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -299,6 +299,7 @@ bool migrate_auto_converge(void);
>  bool migrate_use_multifd(void);
>  bool migrate_pause_before_switchover(void);
>  int migrate_multifd_channels(void);
> +int migrate_multifd_method(void);
>  
>  int migrate_use_xbzrle(void);
>  int64_t migrate_xbzrle_cache_size(void);
> diff --git a/migration/ram.c b/migration/ram.c
> index fcf50e648a..10661e03ae 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -44,6 +44,7 @@
>  #include "page_cache.h"
>  #include "qemu/error-report.h"
>  #include "qapi/error.h"
> +#include "qapi/qapi-types-migration.h"
>  #include "qapi/qapi-events-migration.h"
>  #include "qapi/qmp/qerror.h"
>  #include "trace.h"
> @@ -581,6 +582,7 @@ exit:
>  #define MULTIFD_VERSION 1
>  
>  #define MULTIFD_FLAG_SYNC (1 << 0)
> +#define MULTIFD_FLAG_NOCOMP (1 << 1)
>  
>  /* This value needs to be a multiple of qemu_target_page_size() */
>  #define MULTIFD_PACKET_SIZE (512 * 1024)
> @@ -662,6 +664,8 @@ typedef struct {
>      uint64_t num_pages;
>      /* syncs main thread and channels */
>      QemuSemaphore sem_sync;
> +    /* used for compression methods */
> +    void *data;
>  }  MultiFDSendParams;
>  
>  typedef struct {
> @@ -699,8 +703,153 @@ typedef struct {
>      uint64_t num_pages;
>      /* syncs main thread and channels */
>      QemuSemaphore sem_sync;
> +    /* used for de-compression methods */
> +    void *data;
>  } MultiFDRecvParams;
>  
> +typedef struct {
> +    /* Setup for sending side */
> +    int (*send_setup)(MultiFDSendParams *p, Error **errp);
> +    /* Cleanup for sending side */
> +    void (*send_cleanup)(MultiFDSendParams *p, Error **errp);
> +    /* Prepare the send packet */
> +    int (*send_prepare)(MultiFDSendParams *p, uint32_t used, Error **errp);
> +    /* Write the send packet */
> +    int (*send_write)(MultiFDSendParams *p, uint32_t used, Error **errp);
> +    /* Setup for receiving side */
> +    int (*recv_setup)(MultiFDRecvParams *p, Error **errp);
> +    /* Cleanup for receiving side */
> +    void (*recv_cleanup)(MultiFDRecvParams *p);
> +    /* Read all pages */
> +    int (*recv_pages)(MultiFDRecvParams *p, uint32_t used, Error **errp);
> +} MultiFDMethods;
> +
> +/* Multifd without compression */
> +
> +/**
> + * nocomp_send_setup: setup send side
> + *
> + * For no compression this function does nothing.
> + *
> + * Returns 0 for success or -1 for error
> + *
> + * @p: Params for the channel that we are using
> + * @errp: pointer to an error
> + */
> +static int nocomp_send_setup(MultiFDSendParams *p, Error **errp)
> +{
> +    return 0;
> +}
> +
> +/**
> + * nocomp_send_cleanup: cleanup send side
> + *
> + * For no compression this function does nothing.
> + *
> + * @p: Params for the channel that we are using
> + */
> +static void nocomp_send_cleanup(MultiFDSendParams *p, Error **errp)
> +{
> +    return;
> +}
> +
> +/**
> + * nocomp_send_prepare: prepare date to be able to send
> + *
> + * For no compression we just have to calculate the size of the
> + * packet.
> + *
> + * Returns 0 for success or -1 for error
> + *
> + * @p: Params for the channel that we are using
> + * @used: number of pages used
> + * @errp: pointer to an error
> + */
> +static int nocomp_send_prepare(MultiFDSendParams *p, uint32_t used,
> +                               Error **errp)
> +{
> +    p->next_packet_size = used * qemu_target_page_size();
> +    p->flags |= MULTIFD_FLAG_NOCOMP;
> +    return 0;
> +}
> +
> +/**
> + * nocomp_send_write: do the actual write of the data
> + *
> + * For no compression we just have to write the data.
> + *
> + * Returns 0 for success or -1 for error
> + *
> + * @p: Params for the channel that we are using
> + * @used: number of pages used
> + * @errp: pointer to an error
> + */
> +static int nocomp_send_write(MultiFDSendParams *p, uint32_t used, Error **errp)
> +{
> +    return qio_channel_writev_all(p->c, p->pages->iov, used, errp);
> +}
> +
> +/**
> + * nocomp_recv_setup: setup receive side
> + *
> + * For no compression this function does nothing.
> + *
> + * Returns 0 for success or -1 for error
> + *
> + * @p: Params for the channel that we are using
> + * @errp: pointer to an error
> + */
> +static int nocomp_recv_setup(MultiFDRecvParams *p, Error **errp)
> +{
> +    return 0;
> +}
> +
> +/**
> + * nocomp_recv_cleanup: setup receive side
> + *
> + * For no compression this function does nothing.
> + *
> + * @p: Params for the channel that we are using
> + */
> +static void nocomp_recv_cleanup(MultiFDRecvParams *p)
> +{
> +}
> +
> +/**
> + * nocomp_recv_pages: read the data from the channel into actual pages
> + *
> + * For no compression we just need to read things into the correct place.
> + *
> + * Returns 0 for success or -1 for error
> + *
> + * @p: Params for the channel that we are using
> + * @used: number of pages used
> + * @errp: pointer to an error
> + */
> +static int nocomp_recv_pages(MultiFDRecvParams *p, uint32_t used, Error **errp)
> +{
> +    if (p->flags != MULTIFD_FLAG_NOCOMP) {
> +        error_setg(errp, "multifd %d: flags received %x flags expected %x",
> +                   p->id, MULTIFD_FLAG_NOCOMP, p->flags);

That looks the wrong way around to me - shouldn't that be
   p->flags, MULTIFD_FLAG_NOCOMP
?

> +        return -1;
> +    }
> +    return qio_channel_readv_all(p->c, p->pages->iov, used, errp);
> +}
> +
> +static MultiFDMethods multifd_nocomp_ops = {
> +    .send_setup = nocomp_send_setup,
> +    .send_cleanup = nocomp_send_cleanup,
> +    .send_prepare = nocomp_send_prepare,
> +    .send_write = nocomp_send_write,
> +    .recv_setup = nocomp_recv_setup,
> +    .recv_cleanup = nocomp_recv_cleanup,
> +    .recv_pages = nocomp_recv_pages
> +};
> +
> +static MultiFDMethods *multifd_ops[MULTIFD_COMPRESS__MAX] = {
> +    [MULTIFD_COMPRESS_NONE] = &multifd_nocomp_ops,
> +};
> +
>  static int multifd_send_initial_packet(MultiFDSendParams *p, Error **errp)
>  {
>      MultiFDInit_t msg;
> @@ -898,6 +1047,8 @@ struct {
>      uint64_t packet_num;
>      /* send channels ready */
>      QemuSemaphore channels_ready;
> +    /* multifd ops */
> +    MultiFDMethods *ops;
>  } *multifd_send_state;
>  
>  /*
> @@ -1027,6 +1178,7 @@ void multifd_save_cleanup(void)
>      multifd_send_terminate_threads(NULL);
>      for (i = 0; i < migrate_multifd_channels(); i++) {
>          MultiFDSendParams *p = &multifd_send_state->params[i];
> +        Error *local_err = NULL;
>  
>          if (p->running) {
>              qemu_thread_join(&p->thread);
> @@ -1043,6 +1195,10 @@ void multifd_save_cleanup(void)
>          p->packet_len = 0;
>          g_free(p->packet);
>          p->packet = NULL;
> +        multifd_send_state->ops->send_cleanup(p, &local_err);
> +        if (local_err) {
> +            migrate_set_error(migrate_get_current(), local_err);
> +        }
>      }
>      qemu_sem_destroy(&multifd_send_state->channels_ready);
>      g_free(multifd_send_state->params);
> @@ -1123,7 +1279,14 @@ static void *multifd_send_thread(void *opaque)
>              uint64_t packet_num = p->packet_num;
>              flags = p->flags;
>  
> -            p->next_packet_size = used * qemu_target_page_size();
> +            if (used) {
> +                ret = multifd_send_state->ops->send_prepare(p, used,
> +                                                            &local_err);
> +                if (ret != 0) {
> +                    qemu_mutex_unlock(&p->mutex);
> +                    break;
> +                }
> +            }
>              multifd_send_fill_packet(p);
>              p->flags = 0;
>              p->num_packets++;
> @@ -1140,8 +1303,7 @@ static void *multifd_send_thread(void *opaque)
>              }
>  
>              if (used) {
> -                ret = qio_channel_writev_all(p->c, p->pages->iov,
> -                                             used, &local_err);
> +                ret = multifd_send_state->ops->send_write(p, used, &local_err);
>                  if (ret != 0) {
>                      break;
>                  }
> @@ -1212,6 +1374,7 @@ int multifd_save_setup(Error **errp)
>  {
>      int thread_count;
>      uint32_t page_count = MULTIFD_PACKET_SIZE / qemu_target_page_size();
> +    int ret = 0;
>      uint8_t i;
>  
>      if (!migrate_use_multifd()) {
> @@ -1222,9 +1385,11 @@ int multifd_save_setup(Error **errp)
>      multifd_send_state->params = g_new0(MultiFDSendParams, thread_count);
>      multifd_send_state->pages = multifd_pages_init(page_count);
>      qemu_sem_init(&multifd_send_state->channels_ready, 0);
> +    multifd_send_state->ops = multifd_ops[migrate_multifd_method()];
>  
>      for (i = 0; i < thread_count; i++) {
>          MultiFDSendParams *p = &multifd_send_state->params[i];
> +        int res;
>  
>          qemu_mutex_init(&p->mutex);
>          qemu_sem_init(&p->sem, 0);
> @@ -1240,8 +1405,12 @@ int multifd_save_setup(Error **errp)
>          p->packet->version = cpu_to_be32(MULTIFD_VERSION);
>          p->name = g_strdup_printf("multifdsend_%d", i);
>          socket_send_channel_create(multifd_new_send_channel_async, p);
> +        res = multifd_send_state->ops->send_setup(p, errp);
> +        if (ret == 0) {
> +            ret = res;

How do you handle the errp's here - I think that if is so that you
get the 'ret' from the first thread that fails; but I don't think you're
allowed to call that twice if the first one set it's errp.

> +        }
>      }
> -    return 0;
> +    return ret;
>  }
>  
>  struct {
> @@ -1252,6 +1421,8 @@ struct {
>      QemuSemaphore sem_sync;
>      /* global number of generated multifd packets */
>      uint64_t packet_num;
> +    /* multifd ops */
> +    MultiFDMethods *ops;
>  } *multifd_recv_state;
>  
>  static void multifd_recv_terminate_threads(Error *err)
> @@ -1287,7 +1458,6 @@ static void multifd_recv_terminate_threads(Error *err)
>  int multifd_load_cleanup(Error **errp)
>  {
>      int i;
> -    int ret = 0;
>  
>      if (!migrate_use_multifd()) {
>          return 0;
> @@ -1316,6 +1486,7 @@ int multifd_load_cleanup(Error **errp)
>          p->packet_len = 0;
>          g_free(p->packet);
>          p->packet = NULL;
> +        multifd_recv_state->ops->recv_cleanup(p);
>      }
>      qemu_sem_destroy(&multifd_recv_state->sem_sync);
>      g_free(multifd_recv_state->params);
> @@ -1323,7 +1494,7 @@ int multifd_load_cleanup(Error **errp)
>      g_free(multifd_recv_state);
>      multifd_recv_state = NULL;
>  
> -    return ret;
> +    return 0;
>  }
>  
>  static void multifd_recv_sync_main(void)
> @@ -1388,6 +1559,8 @@ static void *multifd_recv_thread(void *opaque)
>  
>          used = p->pages->used;
>          flags = p->flags;
> +        /* recv methods don't know how to handle the SYNC flag */
> +        p->flags &= ~MULTIFD_FLAG_SYNC;
>          trace_multifd_recv(p->id, p->packet_num, used, flags,
>                             p->next_packet_size);
>          p->num_packets++;
> @@ -1395,8 +1568,7 @@ static void *multifd_recv_thread(void *opaque)
>          qemu_mutex_unlock(&p->mutex);
>  
>          if (used) {
> -            ret = qio_channel_readv_all(p->c, p->pages->iov,
> -                                        used, &local_err);
> +            ret = multifd_recv_state->ops->recv_pages(p, used, &local_err);
>              if (ret != 0) {
>                  break;
>              }
> @@ -1435,9 +1607,11 @@ int multifd_load_setup(Error **errp)
>      multifd_recv_state->params = g_new0(MultiFDRecvParams, thread_count);
>      atomic_set(&multifd_recv_state->count, 0);
>      qemu_sem_init(&multifd_recv_state->sem_sync, 0);
> +    multifd_recv_state->ops = multifd_ops[migrate_multifd_method()];
>  
>      for (i = 0; i < thread_count; i++) {
>          MultiFDRecvParams *p = &multifd_recv_state->params[i];
> +        int ret;
>  
>          qemu_mutex_init(&p->mutex);
>          qemu_sem_init(&p->sem_sync, 0);
> @@ -1448,6 +1622,10 @@ int multifd_load_setup(Error **errp)
>                        + sizeof(ram_addr_t) * page_count;
>          p->packet = g_malloc0(p->packet_len);
>          p->name = g_strdup_printf("multifdrecv_%d", i);
> +        ret = multifd_recv_state->ops->recv_setup(p, errp);
> +        if (ret != 0) {
> +            return ret;
> +        }

same question as the save case above

>      }
>      return 0;
>  }
> -- 
> 2.23.0
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK