Commit 1cf6aa74 authored by Lidong Chen's avatar Lidong Chen Committed by Juan Quintela
Browse files

migration/block: Avoid invoking blk_drain too frequently 



Increase bmds->cur_dirty after submit io, so reduce the frequency
involve into blk_drain, and improve the performance obviously
when block migration.

The performance test result of this patch:

During the block dirty save phase, this patch improve guest os IOPS
from 4.0K to 9.5K. and improve the migration speed from
505856 rsec/s to 855756 rsec/s.

Signed-off-by: default avatarLidong Chen <jemmy858585@gmail.com>
Reviewed-by: default avatarFam Zheng <famz@redhat.com>
Signed-off-by: default avatarJuan Quintela <quintela@redhat.com>
parent 4af245dc

migration/block.c

+3 −0
Original line number Diff line number Diff line
@@ -576,6 +576,9 @@ static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds, 
            }



            bdrv_reset_dirty_bitmap(bmds->dirty_bitmap, sector, nr_sectors);

            sector += nr_sectors;

            bmds->cur_dirty = sector;



            break;

        }

        sector += BDRV_SECTORS_PER_DIRTY_CHUNK;