Re: [Xen-devel] Xen 4.2 TODO / Release Plan

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 31.05.12 at 11:24, Olaf Hering <olaf@xxxxxxxxx> wrote:
> On Tue, May 29, Jan Beulich wrote:
> 
>> >>> On 29.05.12 at 11:32, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
>> > On Mon, 2012-05-14 at 12:14 +0100, Jan Beulich wrote:
>> >> 
>> >> >>> On 14.05.12 at 12:26, Ian Campbell <Ian.Campbell@xxxxxxxxxx>
>> >> wrote:
>> >> > tools, blockers:
>> >> 
>> >> Adjustments needed for qdisk backend to work on non-pvops Linux.
>> > 
>> > Can you remind me what those are please.
>> 
>> "qemu/xendisk: set maximum number of grants to be used"
>> (http://lists.xen.org/archives/html/xen-devel/2012-05/msg00715.html).
>> 
>> Unfortunately I didn't hear back from Olaf regarding the updated
>> value that the supposed v2 of the patch (see the thread), which
>> is at least partly due to him having further problems with the qdisk
>> backend. Olaf - did you ever see gntdev allocation failures again
>> after switching to the higher value?
> 
> I just did a successful installation of sles11sp2 guest on a
> xen-unstable host with changeset 25427:ad348c6575b8, and with the change
> below, and the second attempt I just started seems get through as well.
> 
> I'm sure I used this variant already two weeks ago, and the install
> still failed. Perhaps other changes made during the last two weeks make
> a difference.

That would be odd.

> I will also doublecheck how it goes without this change.
> 
> Olaf
> 
> --- a/hw/xen_disk.c
> +++ b/hw/xen_disk.c
> @@ -536,6 +536,10 @@ static void blk_alloc(struct XenDevice *
>      if (xen_mode != XEN_EMULATE) {
>          batch_maps = 1;
>      }
> +    if (xc_gnttab_set_max_grants(xendev->gnttabdev,
> +               2 * max_requests * BLKIF_MAX_SEGMENTS_PER_REQUEST + 1) < 0)

The + 1 at the end is certainly not needed anymore after the
doubling.

> +        xen_be_printf(xendev, 0, "xc_gnttab_set_max_grants failed: %s\n",
> +                      strerror(errno));
>  }
> 
>  static int blk_init(struct XenDevice *xendev)

So I think I'll re-submit with the doubled values then. That's
in any case better than not setting an upper limit at all on those
older kernels.

Jan


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