Re: [Xen-devel] [PATCH net-next v7 4/9] xen-netback: Introduce TX grant mapping

From: Ian Campbell
Date: Thu Mar 13 2014 - 07:02:48 EST


On Thu, 2014-03-13 at 10:56 +0000, David Vrabel wrote:
> On 13/03/14 10:33, Ian Campbell wrote:
> > On Thu, 2014-03-06 at 21:48 +0000, Zoltan Kiss wrote:
> >> @@ -135,13 +146,31 @@ struct xenvif {
> >> pending_ring_idx_t pending_cons;
> >> u16 pending_ring[MAX_PENDING_REQS];
> >> struct pending_tx_info pending_tx_info[MAX_PENDING_REQS];
> >> + grant_handle_t grant_tx_handle[MAX_PENDING_REQS];
> >>
> >> /* Coalescing tx requests before copying makes number of grant
> >> * copy ops greater or equal to number of slots required. In
> >> * worst case a tx request consumes 2 gnttab_copy.
> >> */
> >> struct gnttab_copy tx_copy_ops[2*MAX_PENDING_REQS];
> >> -
> >> + struct gnttab_map_grant_ref tx_map_ops[MAX_PENDING_REQS];
> >> + struct gnttab_unmap_grant_ref tx_unmap_ops[MAX_PENDING_REQS];
> >
> > I wonder if we should break some of these arrays into separate
> > allocations? Wasn't there a problem with sizeof(struct xenvif) at one
> > point?
>
> alloc_netdev() falls back to vmalloc() if the kmalloc failed so there's
> no need to split these structures.

Is vmalloc space in abundant supply? For some reason I thought it was
limited (maybe that's a 32-bit only limitation?)

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