Re: Disabling verify when norandommap is given

[Jens Axboe <jens.axboe@oracle.com>]

On Thu, Feb 19 2009, Radha Ramachandran wrote:
> Yes, this works for me.
> Thanks for looking into this.

Thanks for testing, I'll double check and test myself tomorrow and then
integrate.


> -radha
> 
> On Thu, Feb 19, 2009 at 10:26 AM, Jens Axboe <jens.axboe@oracle.com> wrote:
> > On Thu, Feb 19 2009, Radha Ramachandran wrote:
> >> Yes, that makes sense for a randwrite operation.
> >> But is it acceptable to allow norandommap with verify for
> >> read/randomread only operations with no writes involved. The case Iam
> >> specifically interested in is doing sequential writes followed by
> >> sequential reads (with verify) and then randomaccess reads (with
> >> verify). For a small enough block size on a large enough drive the
> >> norandommap takes up too much memory.
> >
> > The memory usage is indeed problematic, that is why the option exists.
> > I'd be very happy to slim that down...
> >
> > What you suggest will work, but only for fixed size blocks. Once you
> > have varying block sizes, a given random minimum block offset may be
> > inside a verify block, not at the start of it.
> >
> > So I guess the 'norandommap disables verify' can be relaxed to
> > 'norandommap disables verify IFF non-fixed block sizes are used'. I'm
> > assuming that would work for you? Please try the below patch. If
> > succesful, I'll augment it with an updated HOWTO description.
> >
> > diff --git a/init.c b/init.c
> > index 95c282a..001e5c4 100644
> > --- a/init.c
> > +++ b/init.c
> > @@ -206,6 +206,13 @@ static int setup_rate(struct thread_data *td)
> >        return 0;
> >  }
> >
> > +static int fixed_block_size(struct thread_options *o)
> > +{
> > +       return o->min_bs[DDIR_READ] == o->max_bs[DDIR_READ] &&
> > +               o->min_bs[DDIR_WRITE] == o->max_bs[DDIR_WRITE] &&
> > +               o->min_bs[DDIR_READ] == o->min_bs[DDIR_WRITE];
> > +}
> > +
> >  /*
> >  * Lazy way of fixing up options that depend on each other. We could also
> >  * define option callback handlers, but this is easier.
> > @@ -269,8 +276,10 @@ static int fixup_options(struct thread_data *td)
> >        if (!o->file_size_high)
> >                o->file_size_high = o->file_size_low;
> >
> > -       if (o->norandommap && o->verify != VERIFY_NONE) {
> > -               log_err("fio: norandommap given, verify disabled\n");
> > +       if (o->norandommap && o->verify != VERIFY_NONE
> > +           && !fixed_block_size(o))  {
> > +               log_err("fio: norandommap given for variable block sizes, "
> > +                       "verify disabled\n");
> >                o->verify = VERIFY_NONE;
> >        }
> >        if (o->bs_unaligned && (o->odirect || td->io_ops->flags & FIO_RAWIO))
> >
> > --
> > Jens Axboe
> >
> >

-- 
Jens Axboe