Re: [Qemu-devel] [PATCH 4/6] qcow2: add tracepoints for qcow2_co_write_zeroes

[Denis V. Lunev]

On 05/16/2016 07:32 PM, Eric Blake wrote:
> On 05/14/2016 06:01 AM, Denis V. Lunev wrote:
> > Signed-off-by: Denis V. Lunev <address@hidden>
> > CC: Kevin Wolf <address@hidden>
> > ---
> >   block/qcow2.c | 5 +++++
> >   trace-events  | 2 ++
> >   2 files changed, 7 insertions(+)
> >
> > diff --git a/block/qcow2.c b/block/qcow2.c
> > index 9a54bbd..97bf870 100644
> > --- a/block/qcow2.c
> > +++ b/block/qcow2.c
> > @@ -2435,6 +2435,9 @@ static coroutine_fn int 
> > qcow2_co_write_zeroes(BlockDriverState *bs,
> >       int head = sector_num % s->cluster_sectors;
> >       int tail = (sector_num + nb_sectors) % s->cluster_sectors;
> >   
> > +    trace_qcow2_write_zeroes_start_req(qemu_coroutine_self(), sector_num,
> > +                                       nb_sectors);
> > +
> Can we trace these by byte locations rather than by sector count?
> Ultimately, I think we want to move write_zeroes to a byte-based
> interface, even if we still assert internally that it is at least
> sector-aligned.
we can, but this patches traces for qcow2_co_writev

static coroutine_fn int qcow2_co_writev(BlockDriverState *bs,
                           int64_t sector_num,
                           int remaining_sectors,
                           QEMUIOVector *qiov)
{
    [...]
    trace_qcow2_writev_start_req(qemu_coroutine_self(), sector_num,
                                 remaining_sectors);

Thus I'd better either stick to this implementation or change
all tracepoints in QEMU code.