Re: [Qemu-devel] [PATCH] xen_disk: add discard support

[Olaf Hering <olaf@aepfle.de>]

On Mon, Feb 03, Kevin Wolf wrote:

> Am 30.01.2014 um 16:02 hat Olaf Hering geschrieben:
> > +    case BLKIF_OP_DISCARD:
> > +    {
> > +        struct blkif_request_discard *discard_req = (void *)&ioreq->req;
> > +        bdrv_acct_start(blkdev->bs, &ioreq->acct,
> > +                        discard_req->nr_sectors * BLOCK_SIZE, BDRV_ACCT_WRITE);
> 
> Neither SCSI nor IDE account for discards. I think we should keep the
> behaviour consistent across devices.
> 
> If we do want to introduce accounting for discards, I'm not sure whether
> counting them as writes or giving them their own category makes more
> sense.

This line was just copied. I have to look how virtio does it, maybe I
copied it from there. No problem with removing it from my side.

But I think in the end a discard is also a write, isnt it?


Olaf