[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] TSQ accounting skb->truesize degrades throughput for large packets
Hi Eric I have some questions regarding TSQ and I hope you can shed some light on this. Our observation is that with the default TSQ limit (128K), throughput for Xen network driver for large packets degrades. That's because we now only have 1 packet in queue. I double-checked that skb->len is indeed <64K. Then I discovered that TSQ actually accounts for skb->truesize and the packets generated had skb->truesize > 64K which effectively prevented us from putting 2 packets in queue. There seems to be no way to limit skb->truesize inside driver -- the skb is already constructed when it comes to xen-netfront. My questions are: 1) I see the comment in tcp_output.c saying: "TSQ : sk_wmem_alloc accounts skb truesize, including skb overhead. But thats OK", I don't quite understand why it is OK. 2) presumably other drivers will suffer from this as well, is it possible to account for skb->len instead of skb->truesize? 3) if accounting skb->truesize is on purpose, does that mean we only need to tune that value instead of trying to fix our driver (if there is a way to)? Thanks Wei. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |