On Tue, Jul 29, 2014 at 07:16:46PM +0800, Ruoyu wrote:
> Current epoch_log contains a long nodes array to sync nodes and
> epoch in the cluster. It is simple, but there is a potential
> performance issue because each epoch log occupies nearly 500
> KBytes. If the cluster members change frequently, epoch is lifted
> frequently, more and more unused data is transfered between
> client and server. If we don't find a way, the performance will
> go from bad to worse.
> 
> Although the max node number is 6144, we only use a few of them.
> Therefore, the first solution is using a zero-length array,
> client (dog) and server (sheep) will negotiate an appropriate
> supported node number. This way will spend much less memory and
> will run much faster than before.
> 
> This is patch v2. Comparing it to v1 which is submit on Jul 7,
> internal data structure is changed.
> 
> Signed-off-by: Ruoyu <lian...@ucweb.com>
> ---

You can put change log here like

v3:
 - xxx
 - yyy

v2:
 - zzz

So 'git am' will automatically ignore this.

>  dog/cluster.c            | 40 +++++++++++++++++++++++++++++-----------
>  dog/vdi.c                | 37 ++++++++++++++++++++++++++++---------
>  include/internal_proto.h |  2 +-
>  include/sheepdog_proto.h |  1 +
>  sheep/group.c            |  8 +++++++-
>  sheep/ops.c              | 47 +++++++++++++++++++++++++++++++----------------
>  sheep/store.c            |  6 +++++-
>  7 files changed, 102 insertions(+), 39 deletions(-)
> 
> diff --git a/dog/cluster.c b/dog/cluster.c
> index 188d4f4..508b65a 100644
> --- a/dog/cluster.c
> +++ b/dog/cluster.c
> @@ -141,14 +141,14 @@ static int cluster_format(int argc, char **argv)
>       return EXIT_SUCCESS;
>  }
>  
> -static void print_nodes(const struct epoch_log *logs, int epoch)
> +static void print_nodes(const struct epoch_log *logs, uint16_t flags)
>  {
>       int i, nr_disk;
>       const struct sd_node *entry;
>  
> -     for (i = 0; i < logs[epoch].nr_nodes; i++) {
> -             entry = logs[epoch].nodes + i;
> -             if (logs->flags & SD_CLUSTER_FLAG_DISKMODE) {
> +     for (i = 0; i < logs->nr_nodes; i++) {
> +             entry = logs->nodes + i;
> +             if (flags & SD_CLUSTER_FLAG_DISKMODE) {
>                       for (nr_disk = 0; nr_disk < DISK_MAX; nr_disk++) {
>                               if (entry->disks[nr_disk].disk_id == 0)
>                                       break;
> @@ -169,21 +169,35 @@ static int cluster_info(int argc, char **argv)
>       int i, ret;
>       struct sd_req hdr;
>       struct sd_rsp *rsp = (struct sd_rsp *)&hdr;
> -     struct epoch_log *logs;
> +     struct epoch_log *logs, *log;
> +     char *next_log;
>       int nr_logs, log_length;
>       time_t ti, ct;
>       struct tm tm;
>       char time_str[128];
> +     uint32_t support_nodes;
>  
> -     log_length = sd_epoch * sizeof(struct epoch_log);
> +#define DEFAULT_SUPPORT_NODES 32
> +     support_nodes = DEFAULT_SUPPORT_NODES;
> +     log_length = sd_epoch * (sizeof(struct epoch_log)
> +                     + support_nodes * sizeof(struct sd_node));
>       logs = xmalloc(log_length);
>  
> +retry:
>       sd_init_req(&hdr, SD_OP_STAT_CLUSTER);
>       hdr.data_length = log_length;
> +     hdr.cluster.support_nodes = support_nodes;
>  
>       ret = dog_exec_req(&sd_nid, &hdr, logs);
>       if (ret < 0)
>               goto error;
> +     if (rsp->result == SD_RES_BUFFER_SMALL) {
> +             support_nodes *= 2;
> +             log_length = sd_epoch * (sizeof(struct epoch_log)
> +                             + support_nodes * sizeof(struct sd_node));
> +             logs = xrealloc(logs, log_length);
> +             goto retry;
> +     }
>  
>       /* show cluster status */
>       if (!raw_output)
> @@ -230,10 +244,12 @@ static int cluster_info(int argc, char **argv)
>               printf("Epoch Time           Version\n");
>       }
>  
> -     nr_logs = rsp->data_length / sizeof(struct epoch_log);
> +     nr_logs = rsp->data_length / (sizeof(struct epoch_log)
> +                     + support_nodes * sizeof(struct sd_node));
> +     next_log = (char *)logs;
>       for (i = 0; i < nr_logs; i++) {
> -
> -             ti = logs[i].time;
> +             log = (struct epoch_log *)next_log;
> +             ti = log->time;
>               if (raw_output) {
>                       snprintf(time_str, sizeof(time_str), "%" PRIu64, 
> (uint64_t) ti);
>               } else {
> @@ -241,10 +257,12 @@ static int cluster_info(int argc, char **argv)
>                       strftime(time_str, sizeof(time_str), "%Y-%m-%d 
> %H:%M:%S", &tm);
>               }
>  
> -             printf(raw_output ? "%s %d" : "%s %6d", time_str, 
> logs[i].epoch);
> +             printf(raw_output ? "%s %d" : "%s %6d", time_str, log->epoch);
>               printf(" [");
> -             print_nodes(logs, i);
> +             print_nodes(log, logs->flags);
>               printf("]\n");
> +             next_log = (char *)log->nodes
> +                             + support_nodes * sizeof(struct sd_node);
>       }
>  
>       free(logs);
> diff --git a/dog/vdi.c b/dog/vdi.c
> index 2e3f7b3..6f0b748 100644
> --- a/dog/vdi.c
> +++ b/dog/vdi.c
> @@ -1096,47 +1096,64 @@ static int do_track_object(uint64_t oid, uint8_t 
> nr_copies)
>       struct sd_req hdr;
>       struct sd_rsp *rsp = (struct sd_rsp *)&hdr;
>       const struct sd_vnode *vnode_buf[SD_MAX_COPIES];
> -     struct epoch_log *logs;
> +     struct epoch_log *logs, *log;
> +     char *next_log;
>       int nr_logs, log_length;
> +     uint32_t support_nodes;
>  
> -     log_length = sd_epoch * sizeof(struct epoch_log);
> +#define DEFAULT_SUPPORT_NODES 32
> +     support_nodes = DEFAULT_SUPPORT_NODES;
> +     log_length = sd_epoch * (sizeof(struct epoch_log)
> +                     + support_nodes * sizeof(struct sd_node));
>       logs = xmalloc(log_length);
>  
> +retry:
>       sd_init_req(&hdr, SD_OP_STAT_CLUSTER);
>       hdr.data_length = log_length;
> +     hdr.cluster.support_nodes = support_nodes;
>  
>       ret = dog_exec_req(&sd_nid, &hdr, logs);
>       if (ret < 0)
>               goto error;
>  
> +     if (rsp->result == SD_RES_BUFFER_SMALL) {
> +             support_nodes *= 2;
> +             log_length = sd_epoch * (sizeof(struct epoch_log)
> +                             + support_nodes * sizeof(struct sd_node));
> +             logs = xrealloc(logs, log_length);
> +             goto retry;
> +     }
>       if (rsp->result != SD_RES_SUCCESS) {
>               printf("%s\n", sd_strerror(rsp->result));
>               goto error;
>       }
>  
> -     nr_logs = rsp->data_length / sizeof(struct epoch_log);
> +     nr_logs = rsp->data_length / (sizeof(struct epoch_log)
> +                     + support_nodes * sizeof(struct sd_node));
> +     next_log = (char *)logs;
>       for (i = nr_logs - 1; i >= 0; i--) {
>               struct rb_root vroot = RB_ROOT;
>               struct rb_root nroot = RB_ROOT;
>  
> +             log = (struct epoch_log *)next_log;
>               printf("\nobj %"PRIx64" locations at epoch %d, copies = %d\n",
> -                    oid, logs[i].epoch, nr_copies);
> +                    oid, log->epoch, nr_copies);
>               printf("---------------------------------------------------\n");
>  
>               /*
>                * When # of nodes is less than nr_copies, we only print
>                * remaining nodes that holds all the remaining copies.
>                */
> -             if (logs[i].nr_nodes < nr_copies) {
> -                     for (j = 0; j < logs[i].nr_nodes; j++) {
> -                             const struct node_id *n = &logs[i].nodes[j].nid;
> +             if (log->nr_nodes < nr_copies) {
> +                     for (j = 0; j < log->nr_nodes; j++) {
> +                             const struct node_id *n = &log->nodes[j].nid;
>  
>                               printf("%s\n", addr_to_str(n->addr, n->port));
>                       }
>                       continue;
>               }
> -             for (int k = 0; k < logs[i].nr_nodes; k++)
> -                     rb_insert(&nroot, &logs[i].nodes[k], rb, node_cmp);
> +             for (int k = 0; k < log->nr_nodes; k++)
> +                     rb_insert(&nroot, &log->nodes[k], rb, node_cmp);
>               if (logs->flags & SD_CLUSTER_FLAG_DISKMODE)
>                       disks_to_vnodes(&nroot, &vroot);
>               else
> @@ -1148,6 +1165,8 @@ static int do_track_object(uint64_t oid, uint8_t 
> nr_copies)
>                       printf("%s\n", addr_to_str(n->addr, n->port));
>               }
>               rb_destroy(&vroot, struct sd_vnode, rb);
> +             next_log = (char *)log->nodes
> +                             + support_nodes * sizeof(struct sd_node);
>       }
>  
>       free(logs);
> diff --git a/include/internal_proto.h b/include/internal_proto.h
> index 37afb46..d61b5a5 100644
> --- a/include/internal_proto.h
> +++ b/include/internal_proto.h
> @@ -221,7 +221,7 @@ struct epoch_log {
>       uint8_t  __pad[3];
>       uint16_t flags;
>       char drv_name[STORE_LEN];
> -     struct sd_node nodes[SD_MAX_NODES];
> +     struct sd_node nodes[0];
>  };
>  
>  struct vdi_op_message {
> diff --git a/include/sheepdog_proto.h b/include/sheepdog_proto.h
> index 7cfdccb..8b26a8b 100644
> --- a/include/sheepdog_proto.h
> +++ b/include/sheepdog_proto.h
> @@ -165,6 +165,7 @@ struct sd_req {
>                       uint8_t         copy_policy;
>                       uint16_t        flags;
>                       uint32_t        tag;
> +                     uint32_t        support_nodes;
>               } cluster;
>               struct {
>                       uint32_t        old_vid;
> diff --git a/sheep/group.c b/sheep/group.c
> index f53ad0f..cb10301 100644
> --- a/sheep/group.c
> +++ b/sheep/group.c
> @@ -352,7 +352,7 @@ error:
>  int epoch_log_read_remote(uint32_t epoch, struct sd_node *nodes, int len,
>                         time_t *timestamp, struct vnode_info *vinfo)
>  {
> -     char buf[SD_MAX_NODES * sizeof(struct sd_node) + sizeof(time_t)];
> +     char *buf = xzalloc(len + sizeof(time_t));
>       const struct sd_node *node;
>       int ret;
>  
> @@ -369,6 +369,10 @@ int epoch_log_read_remote(uint32_t epoch, struct sd_node 
> *nodes, int len,
>               hdr.obj.tgt_epoch = epoch;
>               hdr.epoch = sys_epoch();
>               ret = sheep_exec_req(&node->nid, &hdr, buf);
> +             if (ret == SD_RES_BUFFER_SMALL) {
> +                     free(buf);
> +                     return -2;

We have tow means to handle error, if it is simple enough, use -1 to indicate
error and 0 for success, but this is not encouraged because we can't propagate
error to the proper layer.

Otherwise, use SD_RES_xxx and it is your choice to handle the error at the
caller or propagate the error to the upper layer.

Either way, -2 is prohibited.

Thanks
Yuan
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