[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH net] xen-netback: Fix handling of skbs requiring too many slots




On 2014/6/4 11:42, Zoltan Kiss wrote:
On 04/06/14 16:09, annie li wrote:

On 2014/6/3 16:30, Zoltan Kiss wrote:
A recent commit (a02eb4 "xen-netback: worse-case estimate in
xenvif_rx_action is
underestimating") capped the slot estimation to MAX_SKB_FRAGS, but
that triggers
the next BUG_ON a few lines down, as the packet consumes more slots than
estimated.
This patch introduces full_coalesce on the skb callback buffer, which
is used in
start_new_rx_buffer() to decide whether netback needs coalescing more
aggresively. By doing that, no packet should need more than
XEN_NETIF_MAX_TX_SIZE / PAGE_SIZE data slots,

(XEN_NETIF_MAX_TX_SIZE+1) / PAGE_SIZE here?

Do you think about the GSO slot? That's why I wrote "data slot", however that's probably not a clear terminology.

What I mean is: XEN_NETIF_MAX_TX_SIZE is 0xFFFF, and XEN_NETIF_MAX_TX_SIZE / PAGE_SIZE turns out to be 15 slots when PAGE_SIZE is 4096. You was trying to use XEN_NETIF_MAX_TX_SIZE as max size of packet - 64k?

I'll add then that excluding GSO slot, as it doesn't carry data directly, therefore it's irrelevant from this point of view.

Correct.:-)

Thanks
Annie

Zoli

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel


 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.