svn commit: r277419 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs

[Andriy Gapon]

On 20/01/2015 15:09, Alexander Motin wrote:
> Author: mav
> Date: Tue Jan 20 13:09:12 2015
> New Revision: 277419
> URL: https://svnweb.freebsd.org/changeset/base/277419
> 
> Log:
>   Allow skipping dmu_buf_will_dirty() call in dsl_dir_transfer_space().
>   
>   dsl_dir_transfer_space() is mostly called after dsl_dir_diduse_space(),
>   which already calls dmu_buf_will_dirty() for the same dbuf and tx, so
>   its duplicate call in those cases will change nothing, only spend time.
>   
>   Skipping this call by four times reduces time spent in dbuf_write_done()
>   and descendants, updating dataset statistics with several congested lock
>   acquisitions.  When rewriting 8K zvol blocks at 1GB/s rate, this reduces
>   CPU time spent inside dbuf_write_done(), according to profiling, from 45%
>   of 683K samples to 18% of 422K.

It probably would make sense to discuss such a change with the upstream
folks.  Or, at the very least, let them know about it.


>   MFC after:	2 weeks
> 
> Modified:
>   head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c
>   head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dir.c
> 
> Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c
> ==============================================================================
> --- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c	Tue Jan 20 12:28:24 2015	(r277418)
> +++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c	Tue Jan 20 13:09:12 2015	(r277419)
> @@ -136,7 +136,7 @@ dsl_dataset_block_born(dsl_dataset_t *ds
>  	dsl_dir_diduse_space(ds->ds_dir, DD_USED_HEAD, delta,
>  	    compressed, uncompressed, tx);
>  	dsl_dir_transfer_space(ds->ds_dir, used - delta,
> -	    DD_USED_REFRSRV, DD_USED_HEAD, tx);
> +	    DD_USED_REFRSRV, DD_USED_HEAD, NULL);
>  }
>  
>  int
> @@ -179,7 +179,7 @@ dsl_dataset_block_kill(dsl_dataset_t *ds
>  		dsl_dir_diduse_space(ds->ds_dir, DD_USED_HEAD,
>  		    delta, -compressed, -uncompressed, tx);
>  		dsl_dir_transfer_space(ds->ds_dir, -used - delta,
> -		    DD_USED_REFRSRV, DD_USED_HEAD, tx);
> +		    DD_USED_REFRSRV, DD_USED_HEAD, NULL);
>  	} else {
>  		dprintf_bp(bp, "putting on dead list: %s", "");
>  		if (async) {
> @@ -2837,7 +2837,7 @@ dsl_dataset_clone_swap_sync_impl(dsl_dat
>  		    origin_head->ds_dir->dd_origin_txg, UINT64_MAX,
>  		    &odl_used, &odl_comp, &odl_uncomp);
>  		dsl_dir_transfer_space(origin_head->ds_dir, cdl_used - odl_used,
> -		    DD_USED_HEAD, DD_USED_SNAP, tx);
> +		    DD_USED_HEAD, DD_USED_SNAP, NULL);
>  	}
>  
>  	/* swap ds_*_bytes */
> 
> Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dir.c
> ==============================================================================
> --- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dir.c	Tue Jan 20 12:28:24 2015	(r277418)
> +++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dir.c	Tue Jan 20 13:09:12 2015	(r277419)
> @@ -1389,7 +1389,7 @@ dsl_dir_diduse_space(dsl_dir_t *dd, dd_u
>  		    accounted_delta, compressed, uncompressed, tx);
>  		dsl_dir_transfer_space(dd->dd_parent,
>  		    used - accounted_delta,
> -		    DD_USED_CHILD_RSRV, DD_USED_CHILD, tx);
> +		    DD_USED_CHILD_RSRV, DD_USED_CHILD, NULL);
>  	}
>  }
>  
> @@ -1397,7 +1397,7 @@ void
>  dsl_dir_transfer_space(dsl_dir_t *dd, int64_t delta,
>      dd_used_t oldtype, dd_used_t newtype, dmu_tx_t *tx)
>  {
> -	ASSERT(dmu_tx_is_syncing(tx));
> +	ASSERT(tx == NULL || dmu_tx_is_syncing(tx));
>  	ASSERT(oldtype < DD_USED_NUM);
>  	ASSERT(newtype < DD_USED_NUM);
>  
> @@ -1405,7 +1405,8 @@ dsl_dir_transfer_space(dsl_dir_t *dd, in
>  	    !(dsl_dir_phys(dd)->dd_flags & DD_FLAG_USED_BREAKDOWN))
>  		return;
>  
> -	dmu_buf_will_dirty(dd->dd_dbuf, tx);
> +	if (tx != NULL)
> +		dmu_buf_will_dirty(dd->dd_dbuf, tx);
>  	mutex_enter(&dd->dd_lock);
>  	ASSERT(delta > 0 ?
>  	    dsl_dir_phys(dd)->dd_used_breakdown[oldtype] >= delta :
> 


-- 
Andriy Gapon