Re: Fwd: xentop reporting zero written sectors

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Mon, Oct 10, 2011 at 04:16:04PM +0100, Andy Burns wrote:
> No response in xen-users, asking developers ....
> 
> ---------- Forwarded message ----------
> 
> Just moving a chunk of files from one filesysstem on xvba to another
> on xvdb, and was monitoring with xentop as it was taking longer than
> expected.
> 
> The VBD_RD  and VBD_WR counters were both clocking-up as expected, as
> was the VBD_RSECT counter, but the VBD_WSECT counter was stuck on
> zero, I toggled on the individual VBD device counters and these showed
> the same (with the RD and WR counters correctly split between my
> source and destination disks)

Huh. Imagine that!
> 
> Is this a long standing "feature" that I've never noticed before or a
> problem that should be reported?

Must be a feature. We would never write code with bugs. Never :-)

I think this new "feature" below will fix it for you:


diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 0bd7143..3e2ca68 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -778,7 +778,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
 
 	if (operation == READ)
 		blkif->st_rd_sect += preq.nr_sects;
-	else if (operation == WRITE || operation == WRITE_FLUSH)
+	else if (operation == WRITE_ODIRECT || operation == WRITE_FLUSH)
 		blkif->st_wr_sect += preq.nr_sects;
 
 	return 0;


Thanks for reporting it!