zfs very poor performance compared to ufs due to lack of cache?

[Kostik Belousov]

On Wed, Sep 08, 2010 at 10:19:48AM +0300, Andriy Gapon wrote:
> on 07/09/2010 10:26 Andriy Gapon said the following:
> > Interesting.  I briefly looked at the code in mappedread(), zfs_vnops.c, and I
> > have a VM question.
> > Shouldn't we mark the corresponding page bits as valid after reading data into
> > the page?
> > I specifically speak of the block that starts with the following line:
> > } else if (m != NULL && uio->uio_segflg == UIO_NOCOPY) {
> > I am taking mdstart_swap as an example and it does m->valid = VM_PAGE_BITS_ALL.
> > 
> 
> I've chatted with and conclusion seems to be that vm_page_set_validclean() call
> should be added at the end of the block.
> 
> Perhaps, something like this:
> 
> --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
> +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
> @@ -500,6 +500,7 @@ again:
>  				sched_unpin();
>  			}
>  			VM_OBJECT_LOCK(obj);
> +			vm_page_set_validclean(m, off, bytes);
Only if error == 0, perhaps ?

>  			vm_page_wakeup(m);
>  			if (error == 0)
>  				uio->uio_resid -= bytes;
> 
> 
> BTW, I think that 'off' variable can be made of 'int' type, as it is an offset
> within a page; no need for int64.
> 
> -- 
> Andriy Gapon
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