Re: [Qemu-devel] [PATCH v2] migration/block: Avoid invoking blk_drain too frequently

[Dr. David Alan Gilbert]

* Fam Zheng (address@hidden) wrote:
> On Wed, 03/15 11:37, Lidong Chen wrote:
> > 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: Lidong Chen <address@hidden>
> > ---
> >  migration/block.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/migration/block.c b/migration/block.c
> > index 6741228..7734ff7 100644
> > --- a/migration/block.c
> > +++ b/migration/block.c
> > @@ -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;
> > -- 
> > 1.8.3.1
> > 
> 
> Nice catch above all, thank you!
> 
> Reviewed-by: Fam Zheng <address@hidden>

Are you taking that via a block pull?

Dave
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK