From: Jason Wang <jasowang@redhat.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: kvm@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] vhost-net: fall back to vmalloc if high-order allocation fails
Date: Fri, 25 Jan 2013 13:15:51 +0800 [thread overview]
Message-ID: <4164122.3gtdQVSA24@jason-thinkpad-t430s> (raw)
In-Reply-To: <kdsslg$ddn$1@ger.gmane.org>
On Friday, January 25, 2013 03:03:13 AM Cong Wang wrote:
> ["Followup-To:" header set to gmane.linux.network.]
>
> On Wed, 23 Jan 2013 at 20:46 GMT, Romain Francoise <romain@orebokech.com>
wrote:
> > Creating a vhost-net device allocates an object large enough (34320 bytes
> > on x86-64) to trigger an order-4 allocation, which may fail if memory if
> >
> > fragmented:
> > libvirtd: page allocation failure: order:4, mode:0x2000d0
> > ...
> > SLAB: Unable to allocate memory on node 0 (gfp=0xd0)
> >
> > cache: size-65536, object size: 65536, order: 4
> > node 0: slabs: 8/8, objs: 8/8, free: 0
> >
> > In that situation, rather than forcing the caller to use regular
> > virtio-net, try to allocate the descriptor with vmalloc().
>
> The real problem is vhost_net struct is really big, it
> should be reduced rather than workarounded like this.
>
Looks like iov in vhost_virtqueue is a little big:
struct iovec iov[UIO_MAXIOV];
Maybe we can use pointer and allocate it like indirect in
vhost_dev_alloc_iovecs().
> > +static void vhost_net_kvfree(void *addr)
> > +{
> > + if (is_vmalloc_addr(addr))
> > + vfree(addr);
> > + else
> > + kfree(addr);
> > +}
> > +
>
> This kind of stuff should really go to mm, not netdev.
>
> --
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prev parent reply other threads:[~2013-01-25 5:15 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-23 20:46 [PATCH] vhost-net: fall back to vmalloc if high-order allocation fails Romain Francoise
2013-01-23 21:04 ` Michael S. Tsirkin
2013-01-28 3:11 ` David Miller
2013-01-28 9:23 ` Romain Francoise
2013-06-28 7:16 ` Romain Francoise
2013-01-24 9:45 ` David Laight
2013-01-24 10:06 ` Michael S. Tsirkin
2013-01-24 10:37 ` David Laight
2013-01-25 3:03 ` Cong Wang
2013-01-25 5:15 ` Jason Wang [this message]
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