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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH Remus v5 2/2] libxc/restore: implement Remus checkpointed restore
On 14/05/15 11:06, Yang Hongyang wrote:
> With Remus, the restore flow should be:
> the first full migration stream -> { periodically restore stream }
>
> Signed-off-by: Yang Hongyang <yanghy@xxxxxxxxxxxxxx>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> CC: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
> CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> tools/libxc/xc_sr_common.h | 14 ++++++
> tools/libxc/xc_sr_restore.c | 113
> ++++++++++++++++++++++++++++++++++++++++----
> 2 files changed, 117 insertions(+), 10 deletions(-)
>
> diff --git a/tools/libxc/xc_sr_common.h b/tools/libxc/xc_sr_common.h
> index f8121e7..3bf27f1 100644
> --- a/tools/libxc/xc_sr_common.h
> +++ b/tools/libxc/xc_sr_common.h
> @@ -208,6 +208,20 @@ struct xc_sr_context
> /* Plain VM, or checkpoints over time. */
> bool checkpointed;
>
> + /* Currently buffering records between a checkpoint */
> + bool buffer_all_records;
> +
> +/*
> + * With Remus, we buffer the records sent by the primary at checkpoint,
> + * in case the primary will fail, we can recover from the last
> + * checkpoint state.
> + * This should be enough because primary only send dirty pages at
> + * checkpoint.
> + */
> +#define MAX_BUF_RECORDS 1024
> + struct xc_sr_record *buffered_records;
> + unsigned buffered_rec_num;
> +
> /*
> * Xenstore and Console parameters.
> * INPUT: evtchn & domid
> diff --git a/tools/libxc/xc_sr_restore.c b/tools/libxc/xc_sr_restore.c
> index 9ab5760..8468ffc 100644
> --- a/tools/libxc/xc_sr_restore.c
> +++ b/tools/libxc/xc_sr_restore.c
> @@ -468,11 +468,69 @@ static int handle_page_data(struct xc_sr_context *ctx,
> struct xc_sr_record *rec)
> return rc;
> }
>
> +static int process_record(struct xc_sr_context *ctx, struct xc_sr_record
> *rec);
> +static int handle_checkpoint(struct xc_sr_context *ctx)
> +{
> + xc_interface *xch = ctx->xch;
> + int rc = 0;
> + unsigned i;
> +
> + if ( !ctx->restore.checkpointed )
> + {
> + ERROR("Found checkpoint in non-checkpointed stream");
> + rc = -1;
> + goto err;
> + }
> +
> + if ( ctx->restore.buffer_all_records )
> + {
> + IPRINTF("All records buffered");
> +
> + /*
> + * We need to set buffer_all_records to false in
> + * order to process records instead of buffer records.
> + * buffer_all_records should be set back to true after
> + * we successfully processed all records.
> + */
> + ctx->restore.buffer_all_records = false;
> + for ( i = 0; i < ctx->restore.buffered_rec_num; i++ )
> + {
> + rc = process_record(ctx, &ctx->restore.buffered_records[i]);
> + if ( rc )
> + goto err;
> + }
> + ctx->restore.buffered_rec_num = 0;
> + ctx->restore.buffer_all_records = true;
> + IPRINTF("All records processed");
> + }
> + else
> + ctx->restore.buffer_all_records = true;
> +
> + err:
> + return rc;
> +}
> +
> static int process_record(struct xc_sr_context *ctx, struct xc_sr_record
> *rec)
> {
> xc_interface *xch = ctx->xch;
> int rc = 0;
>
> + if ( ctx->restore.buffer_all_records &&
> + rec->type != REC_TYPE_END &&
> + rec->type != REC_TYPE_CHECKPOINT )
> + {
> + if ( ctx->restore.buffered_rec_num >= MAX_BUF_RECORDS )
> + {
> + ERROR("There are too many records within a checkpoint");
> + return -1;
> + }
> +
> +
> memcpy(&ctx->restore.buffered_records[ctx->restore.buffered_rec_num++],
> + rec, sizeof(*rec));
> +
> + return 0;
> + }
> +
> switch ( rec->type )
> {
> case REC_TYPE_END:
> @@ -487,12 +545,17 @@ static int process_record(struct xc_sr_context *ctx,
> struct xc_sr_record *rec)
> ctx->restore.verify = true;
> break;
>
> + case REC_TYPE_CHECKPOINT:
> + rc = handle_checkpoint(ctx);
> + break;
> +
> default:
> rc = ctx->restore.ops.process_record(ctx, rec);
> break;
> }
>
> free(rec->data);
> + rec->data = NULL;
>
> if ( rc == RECORD_NOT_PROCESSED )
> {
> @@ -529,6 +592,15 @@ static int setup(struct xc_sr_context *ctx)
> goto err;
> }
>
> + ctx->restore.buffered_records = malloc(
> + MAX_BUF_RECORDS * sizeof(struct xc_sr_record));
> + if ( !ctx->restore.buffered_records )
> + {
> + ERROR("Unable to allocate memory for buffered records");
> + rc = -1;
> + goto err;
> + }
> +
> err:
> return rc;
> }
> @@ -536,7 +608,12 @@ static int setup(struct xc_sr_context *ctx)
> static void cleanup(struct xc_sr_context *ctx)
> {
> xc_interface *xch = ctx->xch;
> + unsigned i;
> +
> + for ( i = 0; i < ctx->restore.buffered_rec_num; i++ )
> + free(ctx->restore.buffered_records[i].data);
>
> + free(ctx->restore.buffered_records);
> free(ctx->restore.populated_pfns);
> if ( ctx->restore.ops.cleanup(ctx) )
> PERROR("Failed to clean up");
> @@ -564,7 +641,27 @@ static int restore(struct xc_sr_context *ctx)
> {
> rc = read_record(ctx, &rec);
> if ( rc )
> - goto err;
> + {
> + if ( ctx->restore.buffer_all_records )
> + goto remus_failover;
> + else
> + goto err;
> + }
> +
> +#ifdef XG_LIBXL_HVM_COMPAT
> + if ( ctx->dominfo.hvm &&
> + (rec.type == REC_TYPE_END || rec.type == REC_TYPE_CHECKPOINT) )
> + {
> + rc = read_qemu(ctx);
> + if ( rc )
> + {
> + if ( ctx->restore.buffer_all_records )
> + goto remus_failover;
> + else
> + goto err;
> + }
> + }
> +#endif
>
> rc = process_record(ctx, &rec);
> if ( rc )
> @@ -572,15 +669,11 @@ static int restore(struct xc_sr_context *ctx)
>
> } while ( rec.type != REC_TYPE_END );
>
> -#ifdef XG_LIBXL_HVM_COMPAT
> - if ( ctx->dominfo.hvm )
> - {
> - rc = read_qemu(ctx);
> - if ( rc )
> - goto err;
> - }
> -#endif
> -
> + remus_failover:
> + /*
> + * With Remus, if we reach here, there must be some error on primary,
> + * failover from the last checkpoint state.
> + */
> rc = ctx->restore.ops.stream_complete(ctx);
> if ( rc )
> goto err;
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