From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [Xen-devel] [PATCH net-next v5 2/9] xen-netback: Change TX path from grant copy to mapping Date: Tue, 18 Feb 2014 18:46:47 +0000 Message-ID: <5303AA97.3010202@citrix.com> References: <1390253069-25507-1-git-send-email-zoltan.kiss@citrix.com> <1390253069-25507-3-git-send-email-zoltan.kiss@citrix.com> <1392745235.23084.60.camel@kazak.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: Zoltan Kiss , , , , , To: Ian Campbell Return-path: In-Reply-To: <1392745235.23084.60.camel@kazak.uk.xensource.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 18/02/14 17:40, Ian Campbell wrote: > On Mon, 2014-01-20 at 21:24 +0000, Zoltan Kiss wrote: >> >> @@ -344,8 +346,26 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid, >> vif->pending_prod = MAX_PENDING_REQS; >> for (i = 0; i < MAX_PENDING_REQS; i++) >> vif->pending_ring[i] = i; >> - for (i = 0; i < MAX_PENDING_REQS; i++) >> - vif->mmap_pages[i] = NULL; >> + spin_lock_init(&vif->dealloc_lock); >> + spin_lock_init(&vif->response_lock); >> + /* If ballooning is disabled, this will consume real memory, so you >> + * better enable it. > > Almost no one who would be affected by this is going to read this > comment. And it doesn't just require enabling ballooning, but actually > booting with some maxmem "slack" to leave space. > > Classic-xen kernels used to add 8M of slop to the physical address space > to leave a suitable pool for exactly this sort of thing. I never liked > that but perhaps it should be reconsidered (or at least raised as a > possibility with the core-Xen Linux guys). I plan to fix the balloon memory hotplug stuff to do the right thing (it's almost there -- it just tries to overlap the new memory with existing stuff). David